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Electricity - Coggle Diagram
Electricity
Definitions
Electrical current
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It is measured in coulombs and one electron carries 1.6x10^-19 coulombs of charge. Current is equal to C (charge)/s (second)
Current is measured using an ammeter, which is connected in series with a circuit. This is because an ammeter has a negligible resistance and thus, it has to be connected in series as if it were connected in parallel, current will bypass the resistor and flow through the path of the ammeter, causing a short circuit
Potential difference
Potential difference across a conductor is the measure of the work done in moving 1 coulombs of charge across it.
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potential difference is measured using a voltmeter that is connected in parallel to a circuit because an ideal voltmeter has infinite resistance and is supposed to act as a roadblock to prevent current from splitting and passing through the path of the voltmeter.
Electromotive force
Electromotive force is the measure of the work done or energy provided by a power source in driving a unit of charge round a complete circuit.
Parallel cells
If the cells are arranged in paralle, then the energy required to move charges across the load is equally contributed by each cell.
Cells in series
If the cell is connected in series, the total emf will be the sum of the voltages of each cell
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Ohm's law
Ohm's law states that the current passing through a conductor is directly proportional to the potential difference between its end should the physical conditions and temperature remain constant. This means that the V against I graph is a linear graph with a constant gradient (R is constant), that passes through origin
Ohmic conductors
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The V against I graph is a linear graph that passes through origin, and has a constant gradient (V/I gives resistance that is a constant)
For example, a pure metal is an example of an ohmic conductor
Non ohmic conductors
Non-ohmic conductors are conductors that do not obey the ohms law, as they have resistance that can vary, meaning their V against I graphs are not linear graphs and the ratio of V/I is not constant
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Transducers
Transducers are electrical or electronic devices that convert energy from one form to another. They respond to variations in physical quantities, such as light and temperature, and thus acts as an interface between the environment and an electronic system
Input transducers
Input transducers are transducers that convert variations in physical quantities to electrical signals, and includes microphones, light-dependent resistors and thermistors
Thermistors
The resistance of a thermistor decreases with increasing temperature. It can be used for temperature control and measurement, and as temperature increase, resistance decreases, thus increasing output voltage
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Output transducers
Output transducers are those that convert electrical signals to variations in physical quantities, and includes loudspeakers, voltmeters, ammeters and light emitting diodes.
Resistance
Resistance
Resistance of a component is defined as the ratio of potential difference across the component to the amount of current flowing through it
Resistance measures the degree to which an electrical component opposes the movement of electrons, or the pathway of current
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Resistance determines the amount of current that is able to flow through a circuit. The greater the resistance, the smaller the size of current.
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Resistors
Types of resistors
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Variable resistors
A variable resistor is one where the resistance can be changed. When resistance changes, the size of current also changes.
A resistor is a component in an electrical circuit that controls the size of current flowing through the circuit