Revision/ Ch 8/ Q7
Q1
A screen is
separated from a double-slit source by 1.20 m. The distance between the two
slits is 0.030 mm. The second-order bright fringe (m = 2) is measured to be
4.50 cm from the centerline. Determine
(a) the wavelength of the light and
(b) the distance between adjacent bright fringes.
[563 nm, 2.25 cm]
Q2
Semiconductors
such as silicon are used to fabricate solar cells, devices that generate electric
energy when exposed to sunlight. Solar cells are often coated with a
transparent thin film, such as silicon monoxide (SiO; n = 1.45), to minimize
reflective losses (Fig. 24.11). A silicon solar cell (n = 3.50) is coated with
a thin film of SiO for this purpose. Assuming normal incidence, determine the
minimum thickness of the film that will produce the least reflection at a
wavelength of 552 nm.
[95.2 nm]
Q3
(a) Calculate the minimum thickness of a soap-bubble film (n = 1.33)
that will result in
constructive interference in the reflected light if the
film is illuminated by light with
wavelength 602 nm in free space.
(b) Recalculate the minimum thickness for constructive
interference when the soap-bubble
film is on top of a glass slide with n =
1.50.
[113 nm, 226 nm]
Q4
Light of
wavelength 5.80 ´ 102 nm is incident on a slit of
width 0.300 mm. The observing screen is placed 2.00 m from the slit. Find the
positions of the first dark fringes and the width of the central bright fringe.
[3.86 ´ 10-3 m, 7.72 ´ 10-3 m]
Q5
Monochromatic
light from a helium–neon laser (l = 632.8 nm)
is incident normally on a diffraction grating containing 6.00 ´ 103 lines/cm. Find the angles
at which one would observe the first-order maximum, the second-order maximum,
and so forth.
[22.3o, 49.3o]
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