Question

In Young?s double slit experiment, to increase the fringe width

• A. the wavelength of the source is increased
• B. the source is moved towards the slit
• C. the source is moved away from the slit
• D. the slit separation is increased

Answer 1

Answer: (A)

the wavelength of the source is increased

Answer 2

Increase the fringe width depend only the wavelength of the source is increased.
By Young's double slit experiment
$W=\frac{D \lambda}{d}$
According to equation, the fringe width is directly proportional to $\lambda$