G482 OCR Physics A Revision Notes - Unit 3 (DC Circuits)

When a circuit is in series, the voltage is shared and the current remains constant when components are added to the circuit.

When a circuit is in parallel, the voltage remains constant and the current is shared when components are added to the circuit.

Circuit Symbols:

Kirchhoff's Second Law states that the sum of the e.m.f's is equal to the sum of the p.d's around the same loop in a circuit. This is because of a conservation of energy: energy cannot be created or destroyed, so it must be used up within a circuit.

All sources of e.m.f. have internal resistance. For example, a battery has internal resistance due to the chemicals inside of it. In a power supply, it would be the wires and components within it.

The terminal p.d. is the p.d. across the load (external) resistance. The terminal…