Question

Find the thickness of a plate which will produce a change in optical path equal to half the wavelength l of the light passing through it normally. The refractive index of the plate is m -

• A. $\frac{\lambda}{4(\mu –1)}$
• B. $\frac{2\lambda}{4(\mu –1)}$
• C. $\frac{\lambda}{(\mu –1)}$
• D. $\frac{\lambda}{8(\mu –1)}$

Answer 1

Answer: (B)

$\frac{2\lambda}{4(\mu –1)}$

Answer 2

Dx = (m _ 1)t

$\frac{\lambda}{2}$ = (m _ 1) t or t = $\frac{\lambda}{2(\mu –1)}$