GCSE Physics Edexcel P2 Topic 2

These are revision notes I made myself. I got A* in the Physics GCSE exam and 80 UMS (full marks) in the P2 exam using only these notes.

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P2 Topic 2: Controlling and using electric currents
Electric current and potential difference
1. Current: is the rate of flow of charge around the circuit. Current will only flow through a component if there
is a voltage across that compound. It is measured in Amperes, A.
2. Voltage/potential difference: is the driving force that pushes the current around; "electrical pressure".
It is measured in volts, V.
3. Resistance: is anything in the circuit that slows the flow down. It is measured in ohms, .
4. There is a balance: The voltage is trying to push the current round the circuit whilst the resistance opposes
it. The relative sizes of the voltage decide how big the current will be:
If you increase the voltage more current will flow.
If you increase the resistance less current will flow (or more voltage required to keep the same current).
Potential Difference: Energy transferred per Unit Charge Passed
When an electrical charge (blocks that load and unload with energy) goes through a change in potential
difference, energy is transferred.
Energy is supplied to the charge at the power source to raise it through voltage.
The charge gives up this energy when it falls through any voltage drop in components elsewhere in the
circuit.
The bigger the change in voltage, the more energy is transferred for a given amount of charge passing
through the circuit. 1 volt = 1 joule/coulomb.
This means a battery with a bigger voltage will supply more energy to the circuit for every coulomb of charge
which flows round it, because the charge is raised up higher at the start, and more energy will be dissipated
in the circuit too.
Conservation of current
In a parallel circuit:
Each component is separately connected to the positive and negative of the supply.
There are junctions where the current either splits or rejoins. Current doesn't get used up or lost ­ it is
conserved. As a result, the total current entering a junction is equal to the total current leaving a junction.

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Resistance
The Ammeter: This measures the current flowing
along the component. It must be placed in series.
The Voltmeter: This measures the voltage or
potential difference across the component. It
must be placed parallel around the component
under test ­ not around the variable resistor of
the cell.
The Relationship between voltage, current and
resistance
This circuit is a very basic circuit used for testing
components and getting
voltage-current graphs.…read more

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Diode
Current will only flow in one direction in a diode.
Light dependent resistors
These are a special type of resistor that changes its resistance depending on how much light there is.
o In bright light, resistance falls.
o In darkness, the resistance is the highest.
Thermistors
These are similar to light dependent resistors but they depend on temperature.
o In hot conditions, the resistance drops.
o In cool conditions, the resistance goes up.…read more

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An appliance with a high power rating transfers a lot energy in a short time.
The energy comes from the current running through it. This means an appliance with a high power rating will
draw a large current from its supply.
Power is measured in watts.…read more

Comments

Mist

hi, do you have any chemistry notes for c1 ,c2, c3

Nowshin

Do you have any chemistry notes for edexcel c1,c2, and c3?

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