Electricity - P4

• An ohmic device is one that follows ohm’s law (easy enough).
• It is where the current is directly proportional to potential difference (voltage).
• This would show a straight line on a graph.
• An example of an ohmic device would be a resistor at a constant temperature.

In a series circuit, the current is the same but voltage is different.

Potential difference is the electrical potential between two points and is also referred to as voltage.

Voltmeters are always connected in parallel but don’t count as part of the actual circuit.

Total Voltage = V1 + V2 + ...

Current = I1 = I2 = ...

Total Resistance = R1 + R2

In a parallel circuit, the current is different whilst the voltage remains constant:

The total voltage = V1 = V2 = ...

Ammeters are always connected in series:

The total current = I1 + I2 + ...

The total resistance is less than the resistance of the smallest of the two resistors.

This is because there is more current and therefore a decreases in the total resistance of the circuit.