Question

If one of the two slits in a Young’* double-slit demonstration of the interference of light is covered with a thin filter that transmits only half the light intensity, which of the following occurs?

(A) The fringe pattern disappears.

(B) The bright lines are brighter and the dark lines are darker.

(C) The bright lines and the dark lines are all darker.

(D) The bright lines and the dark lines are all brighter.

(E) The dark lines are brighter and the bright lines are darker.

Answer 1

The correct option is: (E) The dark lines are brighter and the bright lines are darker.

Explanation:

This is still a double slit pattern because there is still light making it through both slits. One of the light sources has reduced its amplitude; which means when it meets the second light source it will cause less interference than it originally did. This means less constructive interference and less destructive interference also. So bright spots become less bright, and dark spots become brighter.