A person with her eye relaxed looks through a diffraction grating at a distant monochromatic point source of light. The slits of the grating are vertical. She sees: 

A. one point of light 

B. a hazy horizontal strip of light of the same color as the source 

C. a hazy strip of light varying from violet to red 

D. a sequence of horizontal points of light 

E. a sequence of closely spaced vertical lines

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

For a certain multiple-slit barrier the slit separation is 4 times the slit width. For this system: 

A. the orders of the lines that appear are all multiples of 4 

B. the orders of lines that appear are all multiples of 2 

C. the orders of the missing lines are all multiples of 4 

D. the orders of the missing lines are all multiples of 2 

E. none of the above are true

When the atmosphere is not quite clear, one may sometimes see colored circles concentric with the Sun or the Moon. These are generally not more than a few diameters of the Sun or Moon and invariably the innermost ring is blue. The explanation for this phenomena involves: 

A. reflection 

B. refraction 

C. interference 

D. diffraction 

E. the Doppler effect

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

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 

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 

If we increase the wavelength of the light used to form a double-slit diffraction pattern: 

A. the width of the central diffraction peak increases and the number of bright fringes within the peak increases 

B. the width of the central diffraction peak increases and the number of bright fringes within the peak decreases 

C. the width of the central diffraction peak decreases and the number of bright fringes within the peak increases 

D. the width of the central diffraction peak decreases and the number of bright fringes within the peak decreases 

E. the width of the central diffraction peak increases and the number of bright fringes within the peak stays the same

In the equation φ = (2πa/λ) sin θ for single-slit diffraction, φ is: 

A. the angle to the first minimum 

B. the angle to the second maximum 

C. the phase angle between the extreme rays 

D. Nπ where N is an integer 

E. (N + 1/2)π where N is an integer

In a Young’s experiment, it is essential that the two beams: 

A. have exactly equal intensity 

B. be exactly parallel 

C. travel equal distances 

D. come originally from the same source 

E. be composed of a broad band of frequencies