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

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

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 

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

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 

As more slits with the same spacing are added to a diffraction grating the lines: 

A. spread farther apart 

B. move closer together 

C. become wider 

D. becomes narrower 

E. do not change in position or width

The reason there are two slits, rather than one, in a Young’s experiment is: 

A. to increase the intensity 

B. one slit is for frequency, the other for wavelength 

C. to create a path length difference 

D. one slit is for Vector E fields, the other is for Vector B fields 

E. two slits in parallel offer less resistance

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

The widths of the lines produced by monochromatic light falling on a diffraction grating can be reduced by: 

A. increasing the wavelength of the light 

B. increasing the number of rulings without changing their spacing 

C. decreasing the spacing between adjacent rulings without changing the number of rulings

D. decreasing both the wavelength and the spacing between rulings by the same factor 

E. increasing the number of rulings and decreasing their spacing so the length of the grating remains the same

Waves from two slits are in phase at the slits and travel to a distant screen to produce the second minimum 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. five halves of a wavelength