Physics 121 General Physics
Concept Quizzes
Chapter 37 Interference of Light Waves
Chapter 38 Diffraction Patterns

In a Young's double slit experiment, light and dark fringes are observed on distant screen.

1. What would happen if the wavelength of the light was increased?

	The fringes would become brighter
	More fringes would be visible.
	The distance between dark fringes would decrease.
	The distance between light fringes would increase.

2. What would happen if the distance between the slits was increased?

	The fringes would become brighter
	More fringes would be visible.
	The distance between dark fringes would decrease.
	The distance between light fringes would increase.

A diffraction grating is illuminated with yellow light at normal incidence. The pattern seen on a screen consists of three yellow spots, one at zero degrees (straight through) and one each at +/- 45^o. You now add red light, of equal intensity, coming from the same direction as the yellow light. The pattern now consists of

	Orange spots at 0o and +/- 45o.
	An orange spot at 0o, yellow spots at +/- 45o, and red spots slightly further out.
	An orange spot at 0o, yellow spots at +/- 45o, and red spots slightly closer in.
	None of the above