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

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

A light beam incident on a diffraction grating consists of waves with two different wavelengths. The separation of the two first order lines is great if: 

A. the dispersion is great 

B. the resolution is great 

C. the dispersion is small 

D. the resolution is small 

E. none of the above (line separation does not depend on either dispersion or resolution)

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

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

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 

The intensity at a secondary maximum of a single-slit diffraction pattern is less than the intensity at the central maximum chiefly because: 

A. some Huygens wavelets sum to zero at the secondary maximum but not at the central maximum 

B. the secondary maximum is further from the slits than the central maximum and intensity decreases as the square of the distance 

C. the Huygens construction is not valid for a secondary maximum 

D. the amplitude of every Huygens wavelet is smaller when it travels to a secondary maximum than when it travels to the central maximum 

E. none of the above

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 a double-slit diffraction experiment the number of interference fringes within the central diffraction maximum can be increased by: 

A. increasing the wavelength 

B. decreasing the wavelength 

C. decreasing the slit separation 

D. increasing the slit width 

E. decreasing the slit width 

A parallel beam of monochromatic light is incident on a slit of width 2 cm. The light passing through the slit falls on a screen 2 m away. As the slit width is decreased: 

A. the width of the pattern on the screen continuously decreases 

B. the width of the pattern on the screen at first decreases but then increases 

C. the width of the pattern on the screen increases and then decreases 

D. the width of the pattern on the screen remains the same 

E. the pattern on the screen changes color going from red to blue