What are the units of potential difference?

• A. Volts
• B. Amperes
• C. Watts
• D. Ohms

Answer: (A)

Potential difference is measured in volts and tells you how much energy is transferred per unit charge as charges move between two points. One volt equals one joule per coulomb. In a circuit, this potential difference pushes charges and creates current—the higher the voltage, the more energy per coulomb is delivered to the charges.

Other units describe different things: amperes measure how much charge flows per second, watts measure the rate of energy transfer, and ohms measure how resistant a component is to current. For example, a 9-volt battery provides 9 joules of energy per coulomb of charge moving through the circuit.