The Basic lessons · Basic electronics and theory · B-005-004

Ohm's Law: Voltage, Current, and Resistance

Learn how voltage, current, and resistance relate in a simple circuit using Ohm's Law. Master the three formulas needed to calculate any one value when you know the other two.

This lesson is part of SignalPrep Pro. The subsection's 11 exam questions are free to practise: practise B-005-004.

What this subsection asks

• What is the voltage across a 2-ohm resistor if a current of 0.5 amperes flows through it?
• How is the current in a DC circuit calculated when the voltage and resistance are known?
• How is the resistance in a DC circuit calculated when the voltage and current are known?
• How is the voltage in a DC circuit calculated when the current and resistance are known?
• What is the resistance of a circuit that draws 0.25 amperes from a 12-volt source?
• What value of resistance is required to drop 9 volts with a current of 10 milliamperes?
• If the current flowing through a 50-ohm resistor is 0.44 amperes, what voltage would you measure across the resistor?
• A 30-ohm resistor is connected across a 6-volt battery. What current does it draw?
• What voltage is needed to supply a current of 200 milliamperes to operate a relay that has a resistance of 25 ohms?
• What formula calculates the resistance of a circuit when the voltage and current are known?
• What is the resistance of a circuit if it draws 300 milliamperes from a 3-volt battery?