The spacing between adjacent slits on a diffraction grating is 3λ. The deviation θ of the first order diffracted beam is given by:

A. sin(θ/2) = 1/3 

B. sin(θ/3) = 2/3 

C. sin(θ)=1/3 

D. tan(θ/2) = 1/3 

E. tan(θ)=2/3

In an experiment to measure the wavelength of light using a double slit, it is found that the fringes are too close together to easily count them. To spread out the fringe pattern, one could: 

A. decrease the slit separation 

B. increase the slit separation 

C. increase the width of each slit 

D. decrease the width of each slit 

E. none of these

At the second minimum adjacent to the central maximum of a single-slit diffraction pattern the Huygens wavelet from the top of the slit is 180° out of phase with the wavelet from: 

A. a point one-fourth of the slit width from the top 

B. the midpoint of the slit 

C. a point one-fourth of the slit width from the bottom of the slit 

D. the bottom of the slit 

E. none of these 

A diffraction pattern is produced on a viewing screen by illuminating a long narrow slit with light of wavelength λ. If λ is increased and no other changes are made: 

A. the intensity at the center of the pattern decreases and the pattern expands away from the bright center 

B. the intensity at the center of the pattern increases and the pattern contracts toward the bright center 

C. the intensity at the center of the pattern does not change and the pattern expands away from the bright center 

D. the intensity at the center of the pattern does not change and the pattern contracts toward the bright center 

E. neither the intensity at the center of the pattern nor the pattern itself change

A diffraction pattern is produced on a viewing screen by illuminating a long narrow slit with light of wavelength λ. If the slit width is decreased and no other changes are made: 

A. the intensity at the center of the pattern decreases and the pattern expands away from the bright center 

B. the intensity at the center of the pattern increases and the pattern contracts toward the bright center 

C. the intensity at the center of the pattern does not change and the pattern expands away from the bright center 

D. the intensity at the center of the pattern does not change and the pattern contracts toward the bright center 

E. neither the intensity at the center of the pattern nor the pattern itself change

Monochromatic light is normally incident on a diffraction grating. The m^th order line is at a diffraction angle θ and has width w. A wide single slit is now placed in front of the grating and its width is then slowly reduced. As a result: 

A. both θ and w increase 

B. both θ and w decrease 

C. θ remains the same and w increases 

D. θ remains the same and w decreases 

E. θ decreases and w increases

Waves from two slits are in phase at the slits and travel to a distant screen to produce the third side maximum of the interference pattern. The difference in the distance traveled by the waves is: 

A. half a wavelength 

B. a wavelength 

C. three halves of a wavelength 

D. two wavelengths 

E. three wavelengths

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

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

Light of wavelength is normally incident on some plane optical device. The intensity pattern shown is observed on a distant screen (θ is the angle measured from the normal of the device). The device could be:

A. a single slit of width W 

B. a single slit of width 2W 

C. two narrow slits with separation W 

D. two narrow slits with separation 2W 

E. a diffraction grating with slit separation W