Question

Figure shows four choices for rectangular opening of a source of either sound waves or light waves. The sides have lengths of either L or 2L, with L being 3.0 times the wavelength of the waves. Rank the openings according to the extent of (a) left-right spreading and (b) up-down spreading of the waves due to diffraction, greatest first.

Short answer

1. The rank is 1 and 3 tie followed by tie of 2 and 4
2. The rank is 1 and 2 tie followed by 3 and 4

Step-by-step solution

The given data

Given four choices for rectangular opening of a source of either sound waves or light waves. The sides have lengths of either L or 2L, with L being 3.0 times the wavelength of the waves.

Concept and Formula used

A smaller opening produces a great spreading of waves.

(a) Rank according to left-right spreading

Smaller openings will produce a great spreading of waves (light or sound). To rank the according to left-right spreading, they can be ranked from smallest to largest.

So, the ranking is

(1) and (3) tie, followed by a tie in (2) and (4)

Rank according to up-down spreading

Smaller openings will produce a great spreading of waves (light or sound). To rank the openings according to up-down spreading, they can be ranked from smallest to largest.

So, the ranking is

(1) and (2) tie, followed by a tie in (3) and (4)