Which expression gives energy in joules?

• A. Joules x Seconds
• B. Amps x Volts
• C. Watts x Seconds
• D. Newtons x Meters

Answer: (C)

Energy in joules comes from multiplying the rate of energy transfer by the time over which it occurs. That rate of transfer is power, measured in watts, and time is in seconds. So watts times seconds gives joules—the amount of energy delivered or used over that period.

The other expressions don’t match energy in joules in this context: using joules times seconds would give a unit called joule-seconds, which isn’t energy. Amps times volts gives watts, a rate of energy transfer, not the total energy unless you also multiply by time. Newtons times meters equals joules in mechanical work, but in the electrical sense the standard way to express energy in joules is power times time, i.e., watts × seconds.