Electrical systems part 2

content icon.png

Ohm's Law

We can use Ohm’s Law to calculate potential difference, current and resistance in an electrical circuit OR part of a circuit.

Ohm’s Law is a scientific law that uses resistance and voltage to calculate current.

A resistor is anything that opposes the flow of the current in a circuit (we said to offer resistance) and is measured in ohms (symbol = the omega symbol Ω).

The force that is required to drive the current flow and measured in amperes (or amps for short) and the symbol is A.

The potential difference (voltage) is measured in volts and the symbol is V.

Ohm’s Law states that as voltage increases, current increases IF the resistance remains constant.

Quantity Unit Symbol

Current (I) Ampere A

Voltage (V)

[Potential difference] Volts V

Resistance (R) Ohm Ω

It may help you to remember the formula by using the Ohm’s Law TRIANGLE:

• Electricity is the flow of charges (electrons), invisible but with observable effects.

• Electrical devices require essential components:

  • Input device

  • Processor (control device)

  • Output device

  • Energy source

  • Complete path

  • Load utilizing electric energy

• Ohm's Law links voltage, current, and resistance in circuits with:

  • Current (I) in amperes (A)

  • Voltage (V) in volts (V)

  • Resistance (R) in ohms (Ω)

  • As voltage increases, current increases if resistance remains constant.