question_answer

A person lives in a high-rise building on the bank of a river 50 m wide. Across the river is a well-lit tower of height 40 m. When the person, who is at a height of 10 m, looks through a polarizer at an appropriate angle at light of the tower reflecting from the river surface, he notes that intensity of light coming from distance X from his building is the least and this corresponds to the light coming from light bulbs at height ‘Y’ on the tower. The values of X and Y are respectively close to (refractive index of water\[\simeq \frac{4}{3}\]) [JEE ONLINE 09-04-2013]

A)             25 m, 10 m

B) 13 m, 27 m

C) 22 m, 13 m

D) 17 m, 20 m 

Correct Answer: B

Solution :

[b]

It is the case of Booster angle where reflected and refracted ray both become polarized.

So,

From triangle ABC,

From triangle AEF,