Light from a small region of an ordinary incandescent bulb is passed through a yellow filter and then serves as the source for a Young’s double-slit experiment. Which of the following changes would cause the interference pattern to be more closely spaced? 

A. Use slits that are closer together 

B. Use a light source of lower intensity 

C. Use a light source of higher intensity 

D. Use a blue filter instead of a yellow filter 

E. Move the light source further away from the slits.

Bragg’s law for x-ray diffraction is 2d sin θ = mλ, where θ is the angle between the incident beam and: 

A. a reflecting plane of atoms 

B. the normal to a reflecting plane of atoms 

C. the scattered beam 

D. the normal to the scattered beam 

E. the refracted beam

One of the two slits in a Young’s experiment is painted over so that it transmits only one-half the intensity of the other slit. As a result: 

A. the fringe system disappears 

B. the bright fringes get brighter and the dark ones get darker 

C. the fringes just get dimmer 

D. the dark fringes just get brighter 

E. the dark fringes get brighter and the bright ones get darker

No fringes are seen in a single-slit diffraction pattern if: 

A. the screen is far away 

B. the wavelength is less than the slit width 

C. the wavelength is greater than the slit width 

D. the wavelength is less than the distance to the screen 

E. the distance to the screen is greater than the slit width

In a Young’s double-slit experiment the center of a bright fringe occurs wherever waves from the slits differ in the distance they travel by a multiple of: 

A. a fourth of a wavelength 

B. a half a wavelength 

C. a wavelength 

D. three-fourths of a wavelength 

E. none of the above

Huygens’ construction can be used only: 

A. for light 

B. for an electromagnetic wave

C. if one of the media is vacuum (or air) 

D. for transverse waves 

E. for all of the above and other situations

Binoculars and microscopes are frequently made with coated optics by adding a thin layer of transparent material to the lens surface as shown. One wants:

A. constructive interference between waves 1 and 2 

B. destructive interference between waves 3 and 4 

C. constructive interference between 3 and 4 

D. the coating to be more transparent than the lens 

E. the speed of light in the coating to be less than that in the lens

The dispersion of a diffraction grating indicates: 

A. the resolution of the grating 

B. the separation of lines of the same order 

C. the number of rulings in the grating 

D. the width of the lines 

E. the separation of lines of different order for the same wavelength

Two nearly equal wavelengths of light are incident on an N-slit grating. The two wavelengths are not resolvable. When N is increased they become resolvable. This is because: 

A. more light gets through the grating 

B. the lines get more intense 

C. the entire pattern spreads out 

D. there are more orders present 

E. the lines become more narrow 

Yellow light is viewed by reflection from a thin vertical soap film. Let λ be the wavelength of the light within the film. Why is there a large dark space at the top of the film?

A. no light is transmitted through this part of the film 

B. the film thickness there is λ/4 

C. the film thickness there is much less than λ 

D. the film is too thick in this region for thin film formulas to apply 

E. the reflected light is in the infrared