Which expression correctly represents voltage in terms of power and current?

Which expression correctly represents voltage in terms of power and current?

• A. V = P * I
• B. V = I / P
• C. V = P / I
• D. V = R * I

Answer: (C)

Voltage in terms of power and current comes from the relationship P = V × I, where power (watts) equals voltage (volts) times current (amps). To get voltage using power and current, solve for V: V = P ÷ I. That’s why the correct expression is P divided by I. The other forms don’t fit this specific relationship: V = I × R would use resistance, not power; V = P × I would give incorrect units; V = I ÷ P would also yield the wrong units.

Voltage in terms of power and current comes from the relationship P = V × I, where power (watts) equals voltage (volts) times current (amps). To get voltage using power and current, solve for V: V = P ÷ I. That’s why the correct expression is P divided by I. The other forms don’t fit this specific relationship: V = I × R would use resistance, not power; V = P × I would give incorrect units; V = I ÷ P would also yield the wrong units.