Charge, Current and Voltage
- The rate of flow or charge.
- Measured in Amperes (Amps).
- The charge of 6x10^18 electrons.
- Every coloumb is an amount of negative charge equal to 6x10^18 electrons.
- If 6x10^18 electrons flow past a point in the time of 1 second then the current is equal to 1 amp.
- The amount of energy per unit charge (coulomb)
- The voltage of a battery is equal to the energy in joules provided when a charge of one coulomb passes through the battery.
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- The thinner the wire, the greater the resistance.
- This is because there is less space for electrons to move and there are more collisions between the electrons and ions.
- More frequent collisions mean the temperature of the wire increases.
- The higher the temperature of the wire, the higher the resistance.
- As light intensity decreases the resistance of LDR's increases.
- This means that they can be used effectively in street lights.
- Have constant resistance.
- Ohm's law states that the current through a resistor is proportional to the potential difference provided the temperature is constant.
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energy transferred = potential difference x charge
electric charge = current x time
voltage = current x resistance
electrical power = current x voltage
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