Question

What happens to the fringe pattern, if in the path of one of the slits a glass plate which adsorbs $50\%$ energy is interposed?

• A. Brightness of fringes will decrease but the dark fringe will become brighter
• B. No fringes are observed
• C. The fringes width decrease
• D. None of the above

Answer 1

The correct option is A Brightness of fringes will decrease but the dark fringe will become brighter

When the path difference between the rays is zero than central maxima is formed. When a glass plate of thickness t is introduced the path difference changes by the factor :

$\Delta x=(\mu -1)tt$ t is the thickness of glass plate and $\mu$ is the redfractive index of glass plate. So, the central maxima will shift in the direction of ray. Also the brightness of fringes will decrease but the dark fringe will become brighter.