Physics
Physical Optics
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#9 In a diffraction grating, the number of lines per meter is N. The grating element (d) is equal to:
A) \( N \)
B) \( N^2 \)
C) \( \frac{1}{N} \)
D) \( \frac{1}{N^2} \)
#10 Newton's rings are a classic example of:
A) Interference by division of amplitude
B) Interference by division of wavefront
C) Diffraction
D) Polarization
#11 The condition for destructive interference in a thin film for reflected light, when the film has a higher refractive index than its surroundings, is:
A) \( 2\mu t \cos r = m\lambda \)
B) \( 2\mu t \cos r = (m + \frac{1}{2})\lambda \)
C) \( \mu t \cos r = m\lambda \)
D) \( \mu t \cos r = (m + \frac{1}{2})\lambda \)
#12 What happens to the diffraction pattern from a single slit if the width of the slit is decreased?
A) The pattern becomes narrower
B) The pattern becomes wider
C) The pattern remains unchanged
D) The pattern disappears
#13 In Young's experiment, if white light is used instead of monochromatic light, the central fringe will be:
A) White
B) Dark
C) Red
D) Violet
#14 The ability of an optical instrument to produce separate images of two closely spaced objects is called its:
A) Magnification
B) Resolution
C) Interference
D) Diffraction
#15 According to Rayleigh's criterion, two images are just resolved when the central maximum of one diffraction pattern coincides with the:
A) Central maximum of the other
B) First minimum of the other
C) Second maximum of the other
D) First maximum of the other
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