Question

The questions which follow consist of two statements labelled 'A' and 'R'. Examine each statement

carefully, and decide, if assertion 'A' and reason 'R' are individually correct. If so then decide, whether, the

reason 'R' is the correct explanation of A. Select your answer, using the codes given below, and write your answer

(A) Unit of power is the watt.
(R) Power is the rate of doing work.

• A. Both 'A' and 'R' are correct and 'R' is the correct explanation of 'A'
• B. Both 'A' and 'R' are correct, but 'R' is not the correct explanation of 'A'
• C. 'A' is correct, but 'R' is incorrect
• D. 'A' is incorrect, but 'R' is correct

Answer 1

The correct option is B

Both 'A' and 'R' are correct, but 'R' is not the correct explanation of 'A'

The explanation for Assertion:

1. The SI unit of power is $Watt$.
2. One watt is defined as power consumed when $1joule$ of work is done in $1s$.i.e.,$1\mathrm{W}=\frac{1\mathrm{J}}{1\mathrm{s}}$

The Explanation for Reason:

1. Power is defined as the rate of transfer of energy or rate of doing work.
2. Mathematically, we can say that, $\mathrm{Power}=\frac{W\mathrm{ork}\mathrm{done}}{T\mathrm{ime}\mathrm{spent}}$

Therefore, both assertion and reason are individually correct, but the reason is not the correct explanation of the assertion statement.

Hence, option (B) is correct.