Question

How is electrical power calculated?

Answer 1

Electrical power is calculated using the formula:

Power (P) = Voltage (V) × Current (I)

Where:

Power (P) is measured in watts (W)
Voltage (V) is measured in volts (V)
Current (I) is measured in amperes (A or amps)

This formula is derived from Ohm's law, which states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them:

I = V / R

Where:

I is the current in amperes (A)
V is the voltage in volts (V)
R is the resistance in ohms (Ω)

By rearranging this formula to solve for V (voltage), you get:

V = I × R

Then, substituting this value for V into the power formula, you get:

P = I × (I × R) = I^2 × R

This shows that power is also equal to the square of the current times the resistance. In cases where resistance is constant (as in most electrical devices), the power formula simplifies to P = V × I.

For practical applications, it's essential to use consistent units when plugging values into the formula. For example, if you're given current in amperes and voltage in volts, your result will be in watts, which is the standard unit of power.