Question

An ink mark is made on a piece of paper and a glass slab of thickness $t$ and refractive index $\mu$ is placed on it. If the image of the ink mark appears to be at a distance of $x$ from the top surface of the slab, then the value of $x$ is

• A. $\mu t$
• B. $\frac{t}{\mu}$
• C. $\frac{\mu}{t}$
• D. $\frac{\mu - 1}{t}$
• E. $\frac{t}{\mu - 1}$

Hint:

Apparent depth is always less than actual depth when viewed through a denser medium.

Answer 1

The Correct Option is B

Step 1: The apparent depth $x$ when viewed through a transparent medium of refractive index $\mu$ and thickness $t$ is given by: \[ x = \frac{t}{\mu} \] 
Step 2: This formula arises from the concept of refraction, where light appears to travel a shorter distance in a denser medium due to the bending of rays. 
Step 3: Since the question asks for the apparent depth of the ink mark, we directly use the formula. 
Step 4: Therefore, the correct answer is (B).