Question

In a Young's double slit experiment, if the distance between the slits is halved and the distance of the screen from the slits is doubled, then the fringe width will:

• A. remain same
• B. be doubled
• C. be quadrupled
• D. be halved

Hint:

$\beta \propto D/d$. Increasing $D$ and decreasing $d$ both act to increase the fringe width.

Answer 1

The Correct Option is C

Step 1: Concept
Fringe width $\beta = \frac{\lambda D}{d}$.
Step 2: Analysis
New distance $D' = 2D$ and $d' = d/2$.
New width $\beta' = \frac{\lambda (2D)}{(d/2)} = 4 \frac{\lambda D}{d}$.
Step 3: Conclusion
The fringe width becomes 4 times its original value.
Final Answer: (C)