Question

Monochromatic light passes through two parallel narrow slits and forms an interference pattern on a screen. As the distance between the two slits is decreased, the distance between light bands in the pattern on the screen will
a.decrease.

b.increase.

c.remain the same.

Answer 1

Monochromatic light passes through two parallel narrow slits and forms an interference pattern on a screen. As the distance between the two slits is decreased, the distance between light bands in the pattern on the screen will decrease. The answer is letter A.

Answer 2

Answer:

b.increase.

Explanation:

The distance between the light bands and the distance between the two slits, are related as follows:

$y=\frac{m\lambda D}{d}$

Here, y is the distance between light bands in the pattern, m is the number of light bands observed in the pattern, $\lambda$ is the light's wavelenght, D is the distance between the two slits and the screen where the pattern is observed and d is the distance between the two slits. Thus, as the distance between the two slits is decreased, the distance between light bands will increase.