Question

The following question contains two statements labeled ‘A’ and ‘R’. Examine each statement carefully and decide, if the assertion ‘A’ and reason ‘R’ are individually correct. If so, decide, whether the reason R is the correct explanation of A. Select your answer, using the options given below.

A The top surface of water contained in a beaker appears silvery when held above eye level.

R It is an account of the phenomenon of total internal reflection.

• A. Both ‘A’ and ‘R’ are correct and ‘R’ is the correct explanation of ‘A’
• B. Both ‘A’ and ‘R’ are correct and ‘R’ is the not 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 A

Both ‘A’ and ‘R’ are correct and ‘R’ is the correct explanation of ‘A’

Explanation for Assertion:

1. The light rays undergo refraction when they enter the water beaker from below.
2. These light rays undergo total internal reflection when they strike the water-air interface at an angle greater than 48° which is the critical angle of water.
3. The emergent rays then appear to be coming from the upper surface of the water and appear silvery.

Explanation for reason:

1. Due to total internal reflection, the emergent rays then appear to be coming from the upper surface of the water and appear silvery.

Therefore, the assertion is correct and the reason is the correct explanation of the assertion. Hence, the correct option is A.