Question

Which of the following units is a unit of power?

• A. Kilowatt hour
• B. Watt
• C. Erg
• D. Calorie

Answer 1

Answer: (B)

Explanation of correct option:

Option a)

1. The rate of doing work is called power.
2. Mathematically, power is given as $Power\left(P\right)=\frac{Workdone\left(W\right)}{time\left(t\right)}$
3. The SI unit of power is watt(W).
4. Other units of power is kilowatt(kW) and horsepower(hP)​.

Explanation of incorrect option:

Option b)

1. Kilowatt-hour is the commercial unit of electric energy.
2. ! kilowatt-hour is the amount of electric energy consumed by an electrical ​appliance of power 1kilowatt(kW) when used for 1 hour.

Option c)

1. The capacity of doing work is called energy.
2. The SI unit of energy is the joule(J).
3. The CGS unit of energy is erg.​

Option d)

1. Calorie is an unit of measuring heat ​energy.
2. 1calorie= 4.2J

Thus,

Option a) Watt is the correct option.