Question

The SI unit of power is the watt. Which of the following units are equivalent to the watt?

Answer 1

Answer:

The right option is (A) V.A

Explanation:

Power: This is the rate at which work is done. Or it is the produce of force and velocity. The S.I unit of power is Watt (W). Other units include Horse power(hp), foot-pound per minutes, etc.

Generally, power can be represented as,

Power = Energy/time

P = W/t......................... Equation 1

Where p = power, w = Work or energy, t = time in seconds.

Electrical energy: This is the product of potential difference and the quantity of charge.

∴ W = VQ............................... Equation 2

Where V = potential difference, Q = quantity of charge and W = Energy or Work done.

Also Q = It........................ Equation 3.

where I = current in ampere, t = time in seconds

Substituting equation 3 into equation 3

W = VIt............................ Equation 4.

Also substituting Equation 4 into Equation 1

P = VIt/t = VI = voltage(V)×Current(A)

Therefore the equivalent unit of power is

P = V.A.

The right option is (A) V.A