What is the correct formula for determining wattage?

What is the correct formula for determining wattage?

• A. W = E + I
• B. W = E x I
• C. W = E / I
• D. W = I x R

Answer: (B)

Power is the rate at which energy is transferred in a circuit. It depends on both the push of voltage and the flow of current. The correct relationship multiplies voltage by current: power equals voltage times current. In symbols, P = V × I. This makes sense because voltage is energy per unit charge and current is charge per unit time, so multiplying them gives energy per unit time, i.e., watts. For a quick check, 120 volts with 2 amperes yields 240 watts. The other forms don’t match the units or the meaning of power. Adding voltage and current combines unlike quantities; dividing voltage by current doesn’t yield watts; and current times resistance gives voltage, not power (though there are other valid forms like P = I²R or P = V²/R, which aren’t represented here).

Power is the rate at which energy is transferred in a circuit. It depends on both the push of voltage and the flow of current. The correct relationship multiplies voltage by current: power equals voltage times current. In symbols, P = V × I. This makes sense because voltage is energy per unit charge and current is charge per unit time, so multiplying them gives energy per unit time, i.e., watts. For a quick check, 120 volts with 2 amperes yields 240 watts.

The other forms don’t match the units or the meaning of power. Adding voltage and current combines unlike quantities; dividing voltage by current doesn’t yield watts; and current times resistance gives voltage, not power (though there are other valid forms like P = I²R or P = V²/R, which aren’t represented here).