Question

A beam of light is converging towards a point on the screen. If a plane parallel plate of glass of refraactive in $\mu$ and thickness t is introduced in the path of the beam, the convergent point is shifted

• A. $t[1-\frac{1}{\mu }]$ away
• B. $t[1+\frac{1}{\mu }]$ nearer
• C. $t[1+\frac{1}{\mu }]$ away
• D. $t[1-\frac{1}{\mu }]$ nearer

Answer 1

Answer: (D)

$t[1-\frac{1}{\mu }]$ nearer

When glass plate of thickness t is introduced, the optical path increases by (t/μ).

So the convergence point shifts by t – (t/ μ)

i.e. t[1 – (1/ μ)] nearer.