Which formula expresses electrical power as the product of voltage and current?

• A. V x I
• B. I x R
• C. V^2 / R
• D. R x I

Answer: (A)

Power is the rate at which energy is transferred in a circuit. When a potential difference V drives a current I, the energy transfer per second—the power—is given by multiplying voltage by current: P = V × I. This yields watts when V is in volts and I is in amperes, since 1 watt equals 1 volt × 1 ampere.

The other forms you might see, like I²R or V²/R, come from combining P = VI with Ohm’s law V = IR. They’re just alternative ways to express the same power using different known quantities. For example, P = I²R uses current and resistance, while P = V²/R uses voltage and resistance.

So the direct expression that matches “electrical power as the product of voltage and current” is V × I. Example: a 5 V source with 2 A of current delivers 10 W of power.