Question

The amount of spreading of light after it goes through an opening

a. would be larger if the opening got narrower, just as would happen to sound.

b. the amount of interference after two slits that are as wide as this opening.

c. predicted by the law of refraction applied to openings instead of materials.

d. is independent of the width of the opening and dependent on the wavelength of light.

e. is independent of the wavelength of light and depedent on the width of the opening.

The inability to distinguish two distant light sources looked at through a circular aperture is due to

a. the diffraction pattern of light going past the edges of the circular aperture.

b. a well-known flaw in the psychological perception of distant light.

c. the multiple refractions the two light rays experience on their path to the observer.

d. the excessive nearsightedness of the observer looking through the aperture.

e. the destructive interference of the two light waves before they reach the aperture.

Answer 1

(1) The amount of spreading of light after it goes through and opening will be larger if the opening got narrower, just as would happen to the sound (option (a) is the best answer). There is no law of refraction for slits, and the spreading is dependent on both the width of the slit as well as the wavelength of light. When the width and wavelength are comparable, at that point only we can see the effect of diffraction in light. (The light starts to behave like waves).

(2) The inability to distinguish two distant light sources looked through a circular aperture (like telescope) is due to the diffraction of light when light passes through the edges of the circular aperture (Option (a) is the best answer). There is no problems in the perception of light,no problems with our own eyes (no nearsightedness problem), refractions can't cause two light sources to become indistinguishable, as light will only change paths. The light rays will not go destructive interference before they reach aperture, because the destructive interference depends on where we are keeping our eyes/sensor to collect the information (we can see diffraction pattern only on a screen, not in thin air. And as we move the screen away or towards the slit the patterns will change).