Systems: Sources and functions of components - EduqasFunctions of electronic systems

Ohm’s law

Ohm’s law is one of the most important laws of electrical circuits. It states that the current passing through a conductive material, eg a resistor, is equal to voltage divided by resistance. Ohm’s triangle can be used to remember three important equations:

• voltage (V) - the potential difference between two points, measured in volts (V)
• current (I) - the flow of electricity around a circuit, measured in amps (A)
• resistance (R) - how easily electricity flows through a wire, measured in ohms (Ω)

Example

A resistor has a resistance of 350 ohms (Ω) and a current of 20 milliamps (mA). Calculate the voltage.

V = I × R

There are 1,000 milliamps in 1 amp, so 20 mA ÷ 1,000

= 20 ÷ 1,000 = 0.02 A

V = 350 × 0.02

Voltage = 7 (V)