Question

In Young's double slit experiment, the two slits are illuminated by a monochromatic source of light and interference fringes are observed on a screen placed in front of the slits. If a thin glass plate is placed in front of one of the slits, which of the following will change?

• A. position of central bright fringe
• B. All of the above
• C. angular width of central bright fringe
• D. fringe width

Answer 1

The correct option is A position of central bright fringe

As a thin glass plate is placed in front of one of the sources, the optical path of the waves coming from that source changes. As a result of this, the entire pattern shifts, but there is no change in fringe width or angular width of central bright fringe.
However, as the pattern has shifted, the position of central bright fringe changes.

Hence, $\left(C\right)$ is the correct answer.