From b846e48d03284a54a113429c8401ecbe264eefdd Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Mon, 22 Aug 2022 19:00:04 +0100 Subject: [PATCH 01/23] Last Sync: 2022-08-22 19:00:04 --- .../{Coulombs_Law.md => Coulombs_Laws.md} | 0 Electronics/Physics_of_electricity/Current.md | 2 ++ 2 files changed, 2 insertions(+) rename Electronics/Physics_of_electricity/{Coulombs_Law.md => Coulombs_Laws.md} (100%) diff --git a/Electronics/Physics_of_electricity/Coulombs_Law.md b/Electronics/Physics_of_electricity/Coulombs_Laws.md similarity index 100% rename from Electronics/Physics_of_electricity/Coulombs_Law.md rename to Electronics/Physics_of_electricity/Coulombs_Laws.md diff --git a/Electronics/Physics_of_electricity/Current.md b/Electronics/Physics_of_electricity/Current.md index 2980aad..fbf1b7a 100644 --- a/Electronics/Physics_of_electricity/Current.md +++ b/Electronics/Physics_of_electricity/Current.md @@ -23,6 +23,8 @@ _The diagram below illustrates the flow of current where the circles are electro ![](/img/charge-cylinder.svg) +> Electrons travel very slowly through a conductor. This is in contrast to their intrinsic motion which of course equal to the speed of light (186, 000 miles per second). + ## Formal expression We measure **charge** in Coulombs ($C$). A Coulomb is an aggregate of the charge of thousands of electrons because their individual charge is so small. From 3f3337d114c64ed692faf2ba20494ece9d6f1099 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Mon, 22 Aug 2022 20:00:04 +0100 Subject: [PATCH 02/23] Last Sync: 2022-08-22 20:00:04 --- ...Prefixes_for_units_of_electrical_measurement.md | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/Electronics/Physics_of_electricity/Prefixes_for_units_of_electrical_measurement.md b/Electronics/Physics_of_electricity/Prefixes_for_units_of_electrical_measurement.md index 56b996f..a0363ca 100644 --- a/Electronics/Physics_of_electricity/Prefixes_for_units_of_electrical_measurement.md +++ b/Electronics/Physics_of_electricity/Prefixes_for_units_of_electrical_measurement.md @@ -9,17 +9,17 @@ tags: [physics, electricity, exponents] In electronics we are often dealing with units that are very large or very small, thus we rely on [exponents](/Mathematics/Algebra/Exponents.md) for formal expression. | Prefix | Symbol | Expression as exponent | Expression as decimal value | -|--------|--------|------------------------|-----------------------------| +| ------ | ------ | ---------------------- | --------------------------- | | Giga- | G | $10^9$ | 1,000,000,000 | | Mega- | M | $10^6$ | 1,000,000 | | Kilo- | k | $10^3$ | 1,000 | -| Milli- | m | $10^{-3}$ | 0.001 | -| Micro- | $\mu$ | $10^{-6}$ | 0.0000001 | -| Nano- | n | $10^{-9}$ | 0.0000000001 | -| Pico- | p | $10^{-12}$ | 0.0000000000001 | +| Milli- | m | $10^{-3}$ | 0.001 | +| Micro- | $\mu$ | $10^{-6}$ | 0.0000001 | +| Nano- | n | $10^{-9}$ | 0.0000000001 | +| Pico- | p | $10^{-12}$ | 0.0000000000001 | -For example, with Amps we tend not to use 1 whole amp as this is far too large for most electronics. More common is the milliampere (mA) and the microampere ($\mu$A). +For example, with Amps we tend not to use 1 whole amp as this is far too large for most electronics. More common is the milliampere (mA) and the microampere ($\mu$A). A mA is equal to one thousandth of an ampere: 0.001 A. It takes 1000 milliamperes to equal one ampere. -A $\mu$A is equal to one millionth of an ampere: 0.0000001 A. It takes one million micoramperes to equal one ampere. \ No newline at end of file +A $\mu$A is equal to one millionth of an ampere: 0.0000001 A. It takes one million micoramperes to equal one ampere. From 1df4a7474f62a0e6e37f1b1546cf8a42274879da Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Tue, 23 Aug 2022 20:00:04 +0100 Subject: [PATCH 03/23] Last Sync: 2022-08-23 20:00:04 --- Databases/MongoDB/Complete_example.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Databases/MongoDB/Complete_example.md b/Databases/MongoDB/Complete_example.md index f7d4f23..b5ad54d 100644 --- a/Databases/MongoDB/Complete_example.md +++ b/Databases/MongoDB/Complete_example.md @@ -1,7 +1,7 @@ --- categories: - Databases -tags: [Databases, mongo-db, node-js, mongoose] +tags: [Databases, mongo-db, node-js, mongoose, ABBA] --- # MongoDB connection, set-up and data query: complete example From 3686b29d4e975c01c43ff8dae1a2147cb5068d97 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Wed, 24 Aug 2022 08:30:05 +0100 Subject: [PATCH 04/23] Last Sync: 2022-08-24 08:30:05 --- Electronics/Cells_and_batteries.md | 0 1 file changed, 0 insertions(+), 0 deletions(-) create mode 100644 Electronics/Cells_and_batteries.md diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md new file mode 100644 index 0000000..e69de29 From d2a44f676b6b10b34161a9317dd0fd503a4b3106 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Wed, 24 Aug 2022 09:00:04 +0100 Subject: [PATCH 05/23] Last Sync: 2022-08-24 09:00:04 --- .../Electromagnetism.md | 9 +++ Electronics/Physics_of_electricity/Voltage.md | 58 ++++++++++++++++++- 2 files changed, 66 insertions(+), 1 deletion(-) create mode 100644 Electronics/Physics_of_electricity/Electromagnetism.md diff --git a/Electronics/Physics_of_electricity/Electromagnetism.md b/Electronics/Physics_of_electricity/Electromagnetism.md new file mode 100644 index 0000000..0ecec20 --- /dev/null +++ b/Electronics/Physics_of_electricity/Electromagnetism.md @@ -0,0 +1,9 @@ +--- +categories: + - Electronics +tags: [physics, electricity, electromagnetism] +--- + +# Electromagnetism + +// TODO: Add explanation of the relationship between electricity and magnetism and the underlying physics. diff --git a/Electronics/Physics_of_electricity/Voltage.md b/Electronics/Physics_of_electricity/Voltage.md index 7e90e51..9384eaf 100644 --- a/Electronics/Physics_of_electricity/Voltage.md +++ b/Electronics/Physics_of_electricity/Voltage.md @@ -4,4 +4,60 @@ categories: tags: [physics, electricity] --- -# Voltage +# Voltage + +## Difference of potential and the tranfer of energy + +We noted in the discussion of [current](/Electronics/Physics_of_electricity/Current.md) that current flows when there is difference of potential between two points with negatively charged atoms at one point and positively charged atoms at the other. + +'Difference of potential' is the same thing as voltage. We use the term 'voltage' to denote the potential for current to flow. Voltage is essential to current because it is the force that enables the current to flow. + +Without voltage there can be no current because in their natural state, the electrons in an atom are in random motion with no direction. To produce a current energy must be imparted to the electrons so that they all flow in the same direction. + +Voltage is the application of this energy. Any form of energy that dislodges electrons from atoms can be used to produce current. + +> It is important to realise that in this process energy is not 'created', rather there is a transfer of energy from one form to another. The force applied to generate the current is energy in one form that is converted to another form: electrical current. + +## Voltage sources + +The following are the main sources of voltage: + +- friction +- magnetism +- chemicals +- light +- heat +- pressure + +Energy in these states can be transformed into energy as current. We will review the most common sources below. + +### Magentism (electrical generators) + +Magnetism is used the voltage source in electrical generators by far the most common method of producing powerful and large currents at scale. + +If a conductive wire is passed through a magnetic field voltage will be produced so long as there is motion between the magnetic field and the conductor. A **generator** is a device that generates current in this manner. Generators themselves need to be powered. They can be powered by steam from a nuclear power plant, water, wind, coal or other fossil fuels. + +// TODO: Add symbol + +#### AC/DC + +Depending on how it is wired, a generator can produce **directed current** (DC) or **alternating current** (AC): + +- **Directed current** + + - The electrons flow in only one direction + +- **Alternating current** + - The electrons flow in one direction and then the other + +### Chemicals (cells and batteries) + +The chemical creation of current is the physics behind batteries. Chemical current production produces currents on a smaller and less industrial scale than generators. + +A chemical cell consists in two dissimilar metals such as copper and zinc. We call these the **electrodes**. They are immersed in a salt, acid or alkaline solution. We call these the **electrolytes**. The electrolyte pulls the free electrons from the copper electrode which leaves it imbalanced with a positive charge. The zinc electrode attracts the free electrons from the electrolyte giving it a negative charge, thus a difference of potential is achieved. + +// TODO: Add symbol + +### Light (photovoltaic cells) + +// TODO: Add symbol From 435292ba1391cc1beda2546c50b0c4dcacc9011d Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Thu, 25 Aug 2022 08:00:04 +0100 Subject: [PATCH 06/23] Last Sync: 2022-08-25 08:00:04 --- Electronics/Cells_and_batteries.md | 7 +++++++ Electronics/Physics_of_electricity/Voltage.md | 8 +++----- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index e69de29..1651db0 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -0,0 +1,7 @@ +--- +categories: + - Electronics +tags: [physics, electricity] +--- + +# Cells and batteries diff --git a/Electronics/Physics_of_electricity/Voltage.md b/Electronics/Physics_of_electricity/Voltage.md index 9384eaf..2e83e9b 100644 --- a/Electronics/Physics_of_electricity/Voltage.md +++ b/Electronics/Physics_of_electricity/Voltage.md @@ -37,8 +37,6 @@ Magnetism is used the voltage source in electrical generators by far the most co If a conductive wire is passed through a magnetic field voltage will be produced so long as there is motion between the magnetic field and the conductor. A **generator** is a device that generates current in this manner. Generators themselves need to be powered. They can be powered by steam from a nuclear power plant, water, wind, coal or other fossil fuels. -// TODO: Add symbol - #### AC/DC Depending on how it is wired, a generator can produce **directed current** (DC) or **alternating current** (AC): @@ -56,8 +54,8 @@ The chemical creation of current is the physics behind batteries. Chemical curre A chemical cell consists in two dissimilar metals such as copper and zinc. We call these the **electrodes**. They are immersed in a salt, acid or alkaline solution. We call these the **electrolytes**. The electrolyte pulls the free electrons from the copper electrode which leaves it imbalanced with a positive charge. The zinc electrode attracts the free electrons from the electrolyte giving it a negative charge, thus a difference of potential is achieved. -// TODO: Add symbol - ### Light (photovoltaic cells) -// TODO: Add symbol +Solar energy can be converted to electrical energy through solar panels which are large collections of **photovoltaic cells**. + +When the surfaces of these cells are exposed to light, it dislodges electrons from their orbits around the surface atoms of the cell material. For each cell this only produces a very small amount of energy, therefore large quantities must be used. From bfe47536fca5699860653825dbe3714d142470d0 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Thu, 25 Aug 2022 08:30:05 +0100 Subject: [PATCH 07/23] Last Sync: 2022-08-25 08:30:05 --- Electronics/Physics_of_electricity/Current.md | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/Electronics/Physics_of_electricity/Current.md b/Electronics/Physics_of_electricity/Current.md index fbf1b7a..e240d8b 100644 --- a/Electronics/Physics_of_electricity/Current.md +++ b/Electronics/Physics_of_electricity/Current.md @@ -8,14 +8,15 @@ tags: [physics, electricity] > Electrical current is the movement of electrons from negatively charged atoms to negatively charged atoms when an appropriate external force is applied. -So current is the flow of electrons. Charge is the quantity that flows. +So current is the flow of electrons. Charge is the quantity that flows. > The amount of current is the sum of the charges of the moving electrons past a given point. ## Why current exists + Current exists because of the [first law of electrostatics](/Electronics/Physics_of_electricity/Coulombs_Law.md). -When there is an excess of electrons at one terminal (i.e. negatively charged atoms) and a deficiency of electrons at the other terminal (i.e. positively charged atoms), a _difference of potential_ exists between the two terminals. +When there is an excess of electrons at one terminal (i.e. negatively charged atoms) and a deficiency of electrons at the other terminal (i.e. positively charged atoms), a \*\*difference of potential\_ exists between the two terminals. When the terminals are connected to each other via a conductor (e.g. copper wire) electrons will flow along the conductor. This is provided that there is a source to supply electrons at one end and remove them at the other. We call this force the **voltage source**. @@ -28,9 +29,9 @@ _The diagram below illustrates the flow of current where the circles are electro ## Formal expression We measure **charge** in Coulombs ($C$). A Coulomb is an aggregate of the charge of thousands of electrons because their individual charge is so small. -One Coulomb is equal to the charge of $6.24 \cdot 10 ^{18}$ electrons. +One Coulomb is equal to the charge of $6.24 \cdot 10 ^{18}$ electrons. -We measure **current** in amps. When one coulomb of charge moves past a point in one second it is called an **ampere** (amp) represented as $A$. +We measure **current** in amps. When one coulomb of charge moves past a point in one second it is called an **ampere** (amp) represented as $A$. This relationship is captured in the following equation: @@ -38,14 +39,15 @@ $$ I = \frac{Q}{t} $$ -* $I$ = current measured in amps -* $Q$ = quantity of electrical charge measured in coulombs -* $t$ = time +- $I$ = current measured in amps +- $Q$ = quantity of electrical charge measured in coulombs +- $t$ = time ### Application + _Calculate the current in amps if 9 coulombs of charge flow past a point in an electric circuit in 3 seconds._ $$ I = \frac{9}{3} \\ I = 3 A -$$ \ No newline at end of file +$$ From fa0cce9d6f3879fa80a2521732768356747dd9d9 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Thu, 25 Aug 2022 09:00:04 +0100 Subject: [PATCH 08/23] Last Sync: 2022-08-25 09:00:04 --- Electronics/Cells_and_batteries.md | 36 +++++++++++++++++++ Electronics/Physics_of_electricity/Voltage.md | 7 ++++ 2 files changed, 43 insertions(+) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index 1651db0..fdeae39 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -5,3 +5,39 @@ tags: [physics, electricity] --- # Cells and batteries + +Cells are a [voltage source](/Electronics/Physics_of_electricity/Voltage.md#chemicals-cells-and-batteries) that generate a difference of potential via a positive and negative electrode separated by an electrolytic solution. The electrolytes pull free electrons from one of the materials which creates a positive charge. The other material gains the free electrons creating a negative charge. + +> A battery is a combination of two or more cells. + +> Cells which cannot be recharged are called **primary cells**. Cells which can be recharged are called **secondary cells**. + +## Connecting batteries + +Cells and batteries can be connected to each other in electrical ciruits to increase the overall voltage that is produced. There are three main connection types: + +- series +- parallel +- series-parallel + +### Series connections + +With series connections we distinguish **series aiding** and **series opposing** configurations. + +In the case of series aiding, cells are connected one in front of another with the positive terminal connecting to the negative terminal of the other in a line. + +In this configuration the **same current flows through all the cells**. This is represented mathematically as follows ($T$ stands for time): + +$$ +I_{T} = I_{1} + I_{2} + I_{3} \\ +$$ + +The voltage is the sum of the individual cell voltages (represented here as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field)). + +$$ +E_{T} = E_{1} + E_{2} + E_{3} \\ +$$ + +> Note here we use $E$ instead of $V$. Strictly, $V$ denotes the potential difference whereas $E$ denotes the **electric field**. The electric field is the physical field that surrounds each electric charge and exerts force on all other charges in the field, attracting or repelling them + +// TODO: Add image diff --git a/Electronics/Physics_of_electricity/Voltage.md b/Electronics/Physics_of_electricity/Voltage.md index 2e83e9b..91c1dde 100644 --- a/Electronics/Physics_of_electricity/Voltage.md +++ b/Electronics/Physics_of_electricity/Voltage.md @@ -18,6 +18,13 @@ Voltage is the application of this energy. Any form of energy that dislodges ele > It is important to realise that in this process energy is not 'created', rather there is a transfer of energy from one form to another. The force applied to generate the current is energy in one form that is converted to another form: electrical current. +## Distinguishing _voltage_ from _electric field_ + +It can be confusing that two different symbols often seemed to be used interchangeably when talking about voltage: $V$ and $E$. However, while they broadly point to the same phenomenon there is a difference in emphasis. + +- $V$ stands for volts or voltage conceived purely in terms of the difference in potential between two points: the positive and negative terminals +- $E$ stands for electric field. This is the field that surround each electric charge and exerts force on all other charges in the field, attracting or repelling them. So it is more the physical process that the volatage represents rather than the numerical representation of the potential between the terminals. + ## Voltage sources The following are the main sources of voltage: From 66a9faa8363152d7ef5b409969b93b982ae00f0f Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Thu, 25 Aug 2022 19:30:05 +0100 Subject: [PATCH 09/23] Last Sync: 2022-08-25 19:30:05 --- Databases/MongoDB/Complete_example.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Databases/MongoDB/Complete_example.md b/Databases/MongoDB/Complete_example.md index b5ad54d..835323e 100644 --- a/Databases/MongoDB/Complete_example.md +++ b/Databases/MongoDB/Complete_example.md @@ -1,7 +1,7 @@ --- categories: - Databases -tags: [Databases, mongo-db, node-js, mongoose, ABBA] +tags: [Databases, mongo-db, node-js, mongoose, Abba] --- # MongoDB connection, set-up and data query: complete example From 3d10a757f016f11d02c94b770c244ec59d9011cf Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Thu, 25 Aug 2022 20:00:04 +0100 Subject: [PATCH 10/23] Last Sync: 2022-08-25 20:00:04 --- Databases/MongoDB/Complete_example.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Databases/MongoDB/Complete_example.md b/Databases/MongoDB/Complete_example.md index 835323e..f7d4f23 100644 --- a/Databases/MongoDB/Complete_example.md +++ b/Databases/MongoDB/Complete_example.md @@ -1,7 +1,7 @@ --- categories: - Databases -tags: [Databases, mongo-db, node-js, mongoose, Abba] +tags: [Databases, mongo-db, node-js, mongoose] --- # MongoDB connection, set-up and data query: complete example From de1e74223b4da39ecf2cf8b35cb69e91682ddc21 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Fri, 26 Aug 2022 08:00:04 +0100 Subject: [PATCH 11/23] Last Sync: 2022-08-26 08:00:04 --- Electronics/Cells_and_batteries.md | 2 -- 1 file changed, 2 deletions(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index fdeae39..dcb8ae4 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -38,6 +38,4 @@ $$ E_{T} = E_{1} + E_{2} + E_{3} \\ $$ -> Note here we use $E$ instead of $V$. Strictly, $V$ denotes the potential difference whereas $E$ denotes the **electric field**. The electric field is the physical field that surrounds each electric charge and exerts force on all other charges in the field, attracting or repelling them - // TODO: Add image From 955825c0f54565c7c1b6810555357d49a58fba86 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Fri, 26 Aug 2022 08:30:04 +0100 Subject: [PATCH 12/23] Last Sync: 2022-08-26 08:30:04 --- Electronics/Cells_and_batteries.md | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index dcb8ae4..be40019 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -20,22 +20,32 @@ Cells and batteries can be connected to each other in electrical ciruits to incr - parallel - series-parallel +> The key thing to remember: **cells configured in series increases the overall voltage available** and **cells configured in parallel increases the overall current available** + ### Series connections With series connections we distinguish **series aiding** and **series opposing** configurations. -In the case of series aiding, cells are connected one in front of another with the positive terminal connecting to the negative terminal of the other in a line. +In the case of **series aiding**, cells are connected one in front of another with the positive terminal connecting to the negative terminal of the other in a line. -In this configuration the **same current flows through all the cells**. This is represented mathematically as follows ($T$ stands for time): +In this configuration the same current flows through all the cells, it is not accumulative. We represent this as follows: $$ -I_{T} = I_{1} + I_{2} + I_{3} \\ +I_{T} = I_{1} + I_{2} + I_{3} $$ -The voltage is the sum of the individual cell voltages (represented here as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field)). +However the voltage is accumulative: it is the _sum_ of the individual cell voltages, represented below as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field): $$ E_{T} = E_{1} + E_{2} + E_{3} \\ $$ // TODO: Add image + +In the case of **series opposing**, negative terminals are connected to each other and positive terminals are connected to each other in a series. This doesn't have many applications. + +### Parallel connections + +Parallel connections follow the series opposing (negative to negative, positive to positive) configuration but they are not connected in sequence. + +_The same current flows through all cells. This is represented mathematically as follows ($T$ stands for time)_: From 403c971cf1aac0e269709757daf399e62246dcac Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Fri, 26 Aug 2022 19:00:05 +0100 Subject: [PATCH 13/23] Last Sync: 2022-08-26 19:00:05 --- Electronics/Cells_and_batteries.md | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index be40019..93d24d2 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -14,7 +14,7 @@ Cells are a [voltage source](/Electronics/Physics_of_electricity/Voltage.md#chem ## Connecting batteries -Cells and batteries can be connected to each other in electrical ciruits to increase the overall voltage that is produced. There are three main connection types: +Cells and batteries can be connected to each other in electrical ciruits to increase the overall voltage and current that is produced. There are three main connection types: - series - parallel @@ -22,6 +22,10 @@ Cells and batteries can be connected to each other in electrical ciruits to incr > The key thing to remember: **cells configured in series increases the overall voltage available** and **cells configured in parallel increases the overall current available** +The table below summarises the relative differences: + +![](/img/cell-comparison.svg) + ### Series connections With series connections we distinguish **series aiding** and **series opposing** configurations. @@ -31,7 +35,7 @@ In the case of **series aiding**, cells are connected one in front of another wi In this configuration the same current flows through all the cells, it is not accumulative. We represent this as follows: $$ -I_{T} = I_{1} + I_{2} + I_{3} +I_{T} = I_{1} = I_{2} = I_{3} $$ However the voltage is accumulative: it is the _sum_ of the individual cell voltages, represented below as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field): @@ -40,12 +44,26 @@ $$ E_{T} = E_{1} + E_{2} + E_{3} \\ $$ +Hence why series connections increase voltage but keep current constant. + // TODO: Add image In the case of **series opposing**, negative terminals are connected to each other and positive terminals are connected to each other in a series. This doesn't have many applications. ### Parallel connections -Parallel connections follow the series opposing (negative to negative, positive to positive) configuration but they are not connected in sequence. +In parallel connections all positive terminals are connected to each other and all negative terminals are connected to each other. -_The same current flows through all cells. This is represented mathematically as follows ($T$ stands for time)_: +This time the voltage is the same of each individual cell but the current is the sum of the individual cell currents. So the voltage is constant but the current is accumulative: + +$$ +E_{T} = E_{1} = E_{2} = E_{3} \\ +$$ + +$$ +I_{T} = I_{1} + I_{2} + I_{3} +$$ + +### Series-parrallel + +If we want both a higher voltage and a higher current we can use series-parallel configurations. Connecting cells in series increases the voltage and connecting cells in parellel increases the current so doint both boosts the amount of both quantities. From de74eb9e6cdd1815da8e0056fa09abb100114afb Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Sat, 27 Aug 2022 11:00:04 +0100 Subject: [PATCH 14/23] Last Sync: 2022-08-27 11:00:04 --- Electronics/Cells_and_batteries.md | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index 93d24d2..24c0948 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -46,7 +46,8 @@ $$ Hence why series connections increase voltage but keep current constant. -// TODO: Add image +_Series battery connection:_ +![](/img/seriesbatt-2.svg) In the case of **series opposing**, negative terminals are connected to each other and positive terminals are connected to each other in a series. This doesn't have many applications. @@ -64,6 +65,10 @@ $$ I_{T} = I_{1} + I_{2} + I_{3} $$ +_Parallel battery connection:_ + +![](/img/parallel-batt2.svg) + ### Series-parrallel If we want both a higher voltage and a higher current we can use series-parallel configurations. Connecting cells in series increases the voltage and connecting cells in parellel increases the current so doint both boosts the amount of both quantities. From 931e41c19b376078ba6fbafa326bf0aeab8dc021 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Sat, 27 Aug 2022 12:00:05 +0100 Subject: [PATCH 15/23] Last Sync: 2022-08-27 12:00:05 --- Electronics/Cells_and_batteries.md | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index 24c0948..3ee80c2 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -49,6 +49,10 @@ Hence why series connections increase voltage but keep current constant. _Series battery connection:_ ![](/img/seriesbatt-2.svg) +_Can be represented in a circuit diagram in one of the following two ways: as a series of celss or as a single battery:_ + +![](/img/series-battcircuit.svg) + In the case of **series opposing**, negative terminals are connected to each other and positive terminals are connected to each other in a series. This doesn't have many applications. ### Parallel connections @@ -69,6 +73,10 @@ _Parallel battery connection:_ ![](/img/parallel-batt2.svg) +_Parallel battery circuit diagram:_ + +![](/img/circ-batt-final.svg) + ### Series-parrallel If we want both a higher voltage and a higher current we can use series-parallel configurations. Connecting cells in series increases the voltage and connecting cells in parellel increases the current so doint both boosts the amount of both quantities. From a44d3f6db01544cede9c814f6ceaca590bb82b9a Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Sat, 27 Aug 2022 17:00:04 +0100 Subject: [PATCH 16/23] Last Sync: 2022-08-27 17:00:04 --- Electronics/Cells_and_batteries.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index 3ee80c2..c0cf103 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -47,7 +47,7 @@ $$ Hence why series connections increase voltage but keep current constant. _Series battery connection:_ -![](/img/seriesbatt-2.svg) +![](/img/series-battery-diagram.svg) _Can be represented in a circuit diagram in one of the following two ways: as a series of celss or as a single battery:_ @@ -71,7 +71,7 @@ $$ _Parallel battery connection:_ -![](/img/parallel-batt2.svg) +![](/img/parallel-battery-diagram.svg) _Parallel battery circuit diagram:_ From 79475c2efbeffe4925e1d63c4cd04d9b68ce80c4 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Sun, 28 Aug 2022 09:30:04 +0100 Subject: [PATCH 17/23] Last Sync: 2022-08-28 09:30:04 --- Linux/Monitoring_processes_and_resources.md | 5 +++++ 1 file changed, 5 insertions(+) create mode 100644 Linux/Monitoring_processes_and_resources.md diff --git a/Linux/Monitoring_processes_and_resources.md b/Linux/Monitoring_processes_and_resources.md new file mode 100644 index 0000000..ca97fe9 --- /dev/null +++ b/Linux/Monitoring_processes_and_resources.md @@ -0,0 +1,5 @@ +--- +categories: + - Linux +tags: [journal, systemd, sytems-programming] +--- From 813a0eb326a300a5dedaf922edf4ee908d138036 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Sun, 28 Aug 2022 10:00:04 +0100 Subject: [PATCH 18/23] Last Sync: 2022-08-28 10:00:04 --- .../Shell_Scripting/Processes.md | 32 +++++++++++++++++-- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/Programming_Languages/Shell_Scripting/Processes.md b/Programming_Languages/Shell_Scripting/Processes.md index e0754dd..14a6a40 100644 --- a/Programming_Languages/Shell_Scripting/Processes.md +++ b/Programming_Languages/Shell_Scripting/Processes.md @@ -17,6 +17,31 @@ The command in its most minimal application returns the following 7112 pts/2 00:00:00 ps ``` +With the `-e` modifier we can list more processes: + +``` + PID TTY TIME CMD + 1 ? 00:00:05 systemd + 2 ? 00:00:00 kthreadd + 3 ? 00:00:00 rcu_gp + 4 ? 00:00:00 rcu_par_gp + 5 ? 00:00:00 netns + 7 ? 00:00:00 kworker/0:0H-events_highpri + 9 ? 00:00:00 mm_percpu_wq + 11 ? 00:00:00 rcu_tasks_kthread + 12 ? 00:00:00 rcu_tasks_rude_kthread + 13 ? 00:00:00 rcu_tasks_trace_kthread + 14 ? 00:00:08 ksoftirqd/0 + 15 ? 00:03:20 rcu_preempt + 16 ? 00:00:00 rcub/0 + 17 ? 00:00:00 migration/0 + 18 ? 00:00:00 idle_inject/0 + 20 ? 00:00:00 cpuhp/0 + 21 ? 00:00:00 cpuhp/1 + 22 ? 00:00:00 idle_inject/1 + 23 ? 00:00:00 migration/1 +``` +
pid
Process ID: every currently running process has a unique ID
@@ -43,8 +68,9 @@ The command in its most minimal application returns the following ## Process termination -The general schema is: `kill [pid]`. This allows for process clean-up. If this doesn't succeed you can force with `KILL [pid]` which will terminate the process immediately but is obviously more risky. +The general schema is: `kill [pid]`. This allows for process clean-up. If this doesn't succeed you can force with `KILL [pid]` which will terminate the process immediately but is obviously more risky. We can also start/stop processes with modifiers on `kill`: -* `kill -STOP pid` -* `kill -CONT pid` \ No newline at end of file + +- `kill -STOP pid` +- `kill -CONT pid` From 962b4333da7379939003629f9c159bfeef25469f Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Sun, 28 Aug 2022 11:00:04 +0100 Subject: [PATCH 19/23] Last Sync: 2022-08-28 11:00:04 --- Linux/Monitoring_processes_and_resources.md | 33 ++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/Linux/Monitoring_processes_and_resources.md b/Linux/Monitoring_processes_and_resources.md index ca97fe9..572046f 100644 --- a/Linux/Monitoring_processes_and_resources.md +++ b/Linux/Monitoring_processes_and_resources.md @@ -1,5 +1,36 @@ --- categories: - Linux -tags: [journal, systemd, sytems-programming] +tags: [sytems-programming] --- + +# Monitoring processes and resources + +## Processor time and memory usage: `top`, `htop` etc + +We can use [ps](/Programming_Languages/Shell_Scripting/Processes.md) to list the currently running processes but it does not provide much information about the resource metrics or how the process changes over time. We can use `top` to get more information. + +`top` provides an interactive interface for the information that `ps` displays. It updates in real time and shows the most active processes based on the CPU time that they are utilising. You can also order by memory usage. + +_Here I have pressed `u` to show only the processes associated with my user:_ + +![](/img/htop.png) + +### Main commands + +| Command | Action | +| ------- | ------------------------------- | +| -u | Show processes by selected user | +| M | Sort by memory usage | +| P | Sort by cumulative CPU usage | +| ? | View key and explanation | + +## Files being used by active processes: `lsof` + +`lsof` stands for _list open files_. It lists opened files and the processes using them. Without modifiers it outputs a huge amount of data. The best way to use it is to execute it against a specific PID. For example the below output gives me some useful info about which files VS Code is using: + +![](/img/lsof.png) + +## System calls: `strace` + +A system call is when a process requests a service from the [kernel](/Operating_Systems/The_Kernel.md), for instance an I/O operation to memory. We can trace these system calls with `strace`. From b3756d4fbab01852c5cbf98b52ef850904333cb8 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Mon, 29 Aug 2022 10:30:04 +0100 Subject: [PATCH 20/23] Last Sync: 2022-08-29 10:30:04 --- Electronics/Circuits.md | 5 +++++ 1 file changed, 5 insertions(+) create mode 100644 Electronics/Circuits.md diff --git a/Electronics/Circuits.md b/Electronics/Circuits.md new file mode 100644 index 0000000..406f233 --- /dev/null +++ b/Electronics/Circuits.md @@ -0,0 +1,5 @@ +--- +categories: + - Electronics +tags: [electricity, circuits] +--- From c0a0c1ef4b910b807e9036c7283d06a461fa915d Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Mon, 29 Aug 2022 11:00:04 +0100 Subject: [PATCH 21/23] Last Sync: 2022-08-29 11:00:04 --- Electronics/Cells_and_batteries.md | 13 ++++++++----- Electronics/Circuits.md | 4 ++++ 2 files changed, 12 insertions(+), 5 deletions(-) diff --git a/Electronics/Cells_and_batteries.md b/Electronics/Cells_and_batteries.md index c0cf103..f7730de 100644 --- a/Electronics/Cells_and_batteries.md +++ b/Electronics/Cells_and_batteries.md @@ -32,24 +32,25 @@ With series connections we distinguish **series aiding** and **series opposing** In the case of **series aiding**, cells are connected one in front of another with the positive terminal connecting to the negative terminal of the other in a line. -In this configuration the same current flows through all the cells, it is not accumulative. We represent this as follows: +In this configuration the same current flows through all the cells; it is not cumulative. We represent this as follows: $$ I_{T} = I_{1} = I_{2} = I_{3} $$ -However the voltage is accumulative: it is the _sum_ of the individual cell voltages, represented below as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field): +However the voltage is cumulative: it is the _sum_ of the individual cell voltages, represented below as [electrical field](/Electronics/Physics_of_electricity/Voltage.md#distinguishing-voltage-from-electric-field): $$ E_{T} = E_{1} + E_{2} + E_{3} \\ $$ -Hence why series connections increase voltage but keep current constant. +Thus series connections increase voltage but keep current constant. _Series battery connection:_ + ![](/img/series-battery-diagram.svg) -_Can be represented in a circuit diagram in one of the following two ways: as a series of celss or as a single battery:_ +_Can be represented in a circuit diagram in one of the following two ways: as a series of cells or as a single battery:_ ![](/img/series-battcircuit.svg) @@ -59,7 +60,7 @@ In the case of **series opposing**, negative terminals are connected to each oth In parallel connections all positive terminals are connected to each other and all negative terminals are connected to each other. -This time the voltage is the same of each individual cell but the current is the sum of the individual cell currents. So the voltage is constant but the current is accumulative: +This time the voltage is the same as each individual cell but the current is the sum of the individual cell currents. So the voltage is constant but the current is cumulative: $$ E_{T} = E_{1} = E_{2} = E_{3} \\ @@ -80,3 +81,5 @@ _Parallel battery circuit diagram:_ ### Series-parrallel If we want both a higher voltage and a higher current we can use series-parallel configurations. Connecting cells in series increases the voltage and connecting cells in parellel increases the current so doint both boosts the amount of both quantities. + +// TODO: Add notes on series parallel once I have a better grasp of the basics of circuits. diff --git a/Electronics/Circuits.md b/Electronics/Circuits.md index 406f233..9a8221f 100644 --- a/Electronics/Circuits.md +++ b/Electronics/Circuits.md @@ -3,3 +3,7 @@ categories: - Electronics tags: [electricity, circuits] --- + +# Circuits + +// TODO: Add much more simplified GCSE-level notes on what a circuit is From dc1853b71a608136f9de2c45bf8018dcdd858b8a Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Mon, 29 Aug 2022 11:30:05 +0100 Subject: [PATCH 22/23] Last Sync: 2022-08-29 11:30:05 --- Electronics/Physics_of_electricity/Voltage.md | 45 ++++++++++++++++++- 1 file changed, 43 insertions(+), 2 deletions(-) diff --git a/Electronics/Physics_of_electricity/Voltage.md b/Electronics/Physics_of_electricity/Voltage.md index 91c1dde..3583ea4 100644 --- a/Electronics/Physics_of_electricity/Voltage.md +++ b/Electronics/Physics_of_electricity/Voltage.md @@ -12,7 +12,7 @@ We noted in the discussion of [current](/Electronics/Physics_of_electricity/Curr 'Difference of potential' is the same thing as voltage. We use the term 'voltage' to denote the potential for current to flow. Voltage is essential to current because it is the force that enables the current to flow. -Without voltage there can be no current because in their natural state, the electrons in an atom are in random motion with no direction. To produce a current energy must be imparted to the electrons so that they all flow in the same direction. +Without voltage there can be no current because in their natural state, the electrons in an atom are in random motion with no direction. To produce a current, energy must be imparted to the electrons so that they all flow in the same direction. Voltage is the application of this energy. Any form of energy that dislodges electrons from atoms can be used to produce current. @@ -57,7 +57,7 @@ Depending on how it is wired, a generator can produce **directed current** (DC) ### Chemicals (cells and batteries) -The chemical creation of current is the physics behind batteries. Chemical current production produces currents on a smaller and less industrial scale than generators. +The chemical creation of current is the physics behind [batteries](/Electronics/Cells_and_batteries.md). Chemical current production produces currents on a smaller and less industrial scale than generators. A chemical cell consists in two dissimilar metals such as copper and zinc. We call these the **electrodes**. They are immersed in a salt, acid or alkaline solution. We call these the **electrolytes**. The electrolyte pulls the free electrons from the copper electrode which leaves it imbalanced with a positive charge. The zinc electrode attracts the free electrons from the electrolyte giving it a negative charge, thus a difference of potential is achieved. @@ -66,3 +66,44 @@ A chemical cell consists in two dissimilar metals such as copper and zinc. We ca Solar energy can be converted to electrical energy through solar panels which are large collections of **photovoltaic cells**. When the surfaces of these cells are exposed to light, it dislodges electrons from their orbits around the surface atoms of the cell material. For each cell this only produces a very small amount of energy, therefore large quantities must be used. + +## Voltage rise and voltage drops + +In circuits there are actually two types of voltage: + +1. Voltage rise +2. Voltage drop + +### Voltage rise + +When we introduce potential energy into a ciruit in the form of voltage, this is a voltage rise. The current flows from the negative terminal of the voltage source and returns to the positive terminal of the voltage source. + +A 12V battery connected to a circuit gives it a voltage rise of 12 volts. + +### Voltage drop + +Voltage drop is the corrolary to voltage rise. It is the loss of energy that the electrons of the circuit current experience as a result of encountering resistance. + +As they move through the circuit the electrons encounter a **load** which is what we call resistance to the flow of electrons. As they run into this, they give up their energy. The relinquishing of energy happens in the form of a conversion of electrical energy to heat. The amount lost is equal to the amount of energy imparted by the voltage rise. + +> The voltage drop in a circuit equals the the voltage rise of the circuit because energy cannot be created or destroyed, only changed to another form. When a voltage rise is converted to a voltage drop we say that **the energy has been _consumed_ by the circuit**. + +#### Examples + +- If a 12V source is connected to a 12V lamp, the source supplies a 12V voltage rise and the lamp produces a 12V voltage drop. +- If two identical 6V lamps are connected in series to the same 12V source, each lamp produces a 6V drop for a total of 12 volts +- If two different lamps are connected in series to to a 12V source: a 3V and a 9V lamp, the 9V lamp produces a drop of 9V and the 3V lamp produces a drop of 3V. The sum of the voltage drops equals the voltage rise of 12 volts. + +These examples demonstrate that the voltage rise: voltage drop ratio always evens out. + +## Ground: zero potential + +We use the term **ground** to refer to zero potential - the point at which there is no difference of potential (voltage) that could generate current. + +We need ground to prevent electric shock from appliances and circuits. It keeps all devices at the same potential. + +In domestic settings appliances are **earth grounded**. The name comes from the fact that all appliances will ultimately connect to the earth to neutralise potential. This means there can be no difference of potential between circuits. + +In electronics ground doesn't refer to the specific appliance but is a concept of a zero reference point against which all voltages are measured. A measured voltage will be negative or positive with respect to ground. This said, all circuitry will also have a physical mechanism of discharging potential. + +// TODO: Don't really understand this so return to with better explanation From 767bef7baec59f434eff3c7b466f3f5124d12d07 Mon Sep 17 00:00:00 2001 From: tactonbishop Date: Tue, 30 Aug 2022 09:30:04 +0100 Subject: [PATCH 23/23] Last Sync: 2022-08-30 09:30:04 --- .../Physics_of_electricity/Electromagnetism.md | 6 +++++- Electronics/Physics_of_electricity/Voltage.md | 7 +++++-- markdown-styles.css | 11 +++++++++++ 3 files changed, 21 insertions(+), 3 deletions(-) create mode 100644 markdown-styles.css diff --git a/Electronics/Physics_of_electricity/Electromagnetism.md b/Electronics/Physics_of_electricity/Electromagnetism.md index 0ecec20..b145cc8 100644 --- a/Electronics/Physics_of_electricity/Electromagnetism.md +++ b/Electronics/Physics_of_electricity/Electromagnetism.md @@ -6,4 +6,8 @@ tags: [physics, electricity, electromagnetism] # Electromagnetism -// TODO: Add explanation of the relationship between electricity and magnetism and the underlying physics. +For a long time electricity and magnetism were thought to be separate forces. In the 19th century Maxwell demonstrated that they were interrelated phenomena then Einstein proved with the Special Theory of Relativity that they are aspects of one unified phenomenon. + +The core of the relationship is that a changing magnetic field produces an electric field and conversely, a changing electric field produces a magnetic field. + +https://www.britannica.com/science/electromagnetism diff --git a/Electronics/Physics_of_electricity/Voltage.md b/Electronics/Physics_of_electricity/Voltage.md index 3583ea4..c8a28b1 100644 --- a/Electronics/Physics_of_electricity/Voltage.md +++ b/Electronics/Physics_of_electricity/Voltage.md @@ -10,13 +10,15 @@ tags: [physics, electricity] We noted in the discussion of [current](/Electronics/Physics_of_electricity/Current.md) that current flows when there is difference of potential between two points with negatively charged atoms at one point and positively charged atoms at the other. -'Difference of potential' is the same thing as voltage. We use the term 'voltage' to denote the potential for current to flow. Voltage is essential to current because it is the force that enables the current to flow. +'Difference of potential' is the same thing as voltage. We use the term 'voltage' to denote the propensity for charge to flow from one place to another. Voltage is essential to current because it is the force that enables the current to flow. + +## Distinguishing _voltage_ from _electric field_ Without voltage there can be no current because in their natural state, the electrons in an atom are in random motion with no direction. To produce a current, energy must be imparted to the electrons so that they all flow in the same direction. Voltage is the application of this energy. Any form of energy that dislodges electrons from atoms can be used to produce current. -> It is important to realise that in this process energy is not 'created', rather there is a transfer of energy from one form to another. The force applied to generate the current is energy in one form that is converted to another form: electrical current. +> It is important to realise that in this process energy is not 'created', rather there is a transfer of energy from one form to another. The force applied to generate the currThe Expanse Season 4 ## Distinguishing _voltage_ from _electric field_ @@ -43,6 +45,7 @@ Energy in these states can be transformed into energy as current. We will review Magnetism is used the voltage source in electrical generators by far the most common method of producing powerful and large currents at scale. If a conductive wire is passed through a magnetic field voltage will be produced so long as there is motion between the magnetic field and the conductor. A **generator** is a device that generates current in this manner. Generators themselves need to be powered. They can be powered by steam from a nuclear power plant, water, wind, coal or other fossil fuels. +The Expanse Season 4 #### AC/DC diff --git a/markdown-styles.css b/markdown-styles.css new file mode 100644 index 0000000..35814d8 --- /dev/null +++ b/markdown-styles.css @@ -0,0 +1,11 @@ +* { + font-family: 'Inter'; +} + +pre, code { + font-family: 'Liga Liberation Mono' !important; +} + +code { + font-family: 'Liga Liberation Mono' !important; +} \ No newline at end of file