# P2.3 Electric currents

- electrical current is the rate of flow of charge.

- current in metals is a flow of electrons.

- equation:

charge(coulomb     ,) = current (ampere, A) * time (second,s) 'Q=Ixt

- cells and battery supply direct current.

- direct current ~ movement of charge in one direction.

- altenating current ~ electrons change directions many times each second.

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• Created by: amrik
• Created on: 16-10-13 21:00

## P2.7 Transferring energy

- when there is an electric current in a resistor, there is an energy transfer which heats the reistor. This is a result of collisions between electrons and ions in the lattice.

- advantages of heating effects of an electrical current: this heating is useful in appliances such as electric fires and kettles. These appliances are effectivley large resistors.

-Disadvatages of heating effects of an electrical current: some electrical appliances could create so much waste energy that they becom to hot and may cause burns.

equations:

electrical power (watt, w) = current (amperes, A) * potential diffrence ( volt,v)

energy transfered (joules, j) = potential diffrence (volt,v)* time (second, s)

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