Question

In Young’s double-slit experiment, the wavelength of light is doubled while all other parameters remain unchanged. The fringe width becomes:

• A. Half of the original
• B. Unchanged
• C. Double the original
• D. Four times the original

Hint:

Since $\beta$ is directly proportional to $\lambda$, any modification factor applied to the wavelength is directly transferred to the fringe width.
If $\lambda$ is doubled, $\beta$ is doubled.
If $\lambda$ is halved, $\beta$ is halved.
This direct proportionality simplifies conceptual questions in YDSE.

Answer 1

The Correct Option is C

Step 1: Proportionality.
$\beta \propto \lambda$; doubling $\lambda$ doubles $\beta$.
Answer: Double