*Worked Sample Problems Test 3 Ch: 22,23,24,26*
Chapter 22: Reflection and Refraction of Light
22.1: Calculate a resultant angle from reflections.
Problem: Two mirrors make an angle of 120° with each other, as in Figure 22.5. A ray is
incident on mirror M1 at an angle of 65° to the normal. Find the angle the ray makes with
the normal. Find the angle the ray makes with the normal to M2 after it is reflected from
both mirrors.
22.2 Apply Snell’s law to a slab of glass.
Problem: A light ray of wavelength 589 nm (produced by a sodium lamp) traveling through
air is incident on a smooth, flat slab of crown glass at an angle of 30° to the normal, as
sketched in figure 22.11. Find the angle of refraction, θ
2
.
22.3 Use the index of refraction to determine effect of a medium on light’s speed and
wavelength.
Problem: Light of wavelength 589 nm in vacuum passes through a piece of fused quartz of
index of refraction n=1.458. (a) Find the speed of light in fused quartz. (b) What is the
wavelength of this light in fused quartz? (c) What is the frequency of the light in fused
quartz?
22.4A Apply Snell’s law when a ray passes into and out of another medium.
Problem: A light beam traveling through a transparent medium of index of refraction n1
passes through a thick transparent slab with parallel faces and index of refraction n2 (Fig.
22.12). Show that the emerging beam is parallel to the incident beam.
22.4B Suppose the ray, in air with n=1.00, enters a slab with n=2.50 at a 45.0° angle
with respect to the normal, then exits the bottom of the slab into water, with n=1.33. At
what angle to the normal does the ray leave the slab?
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22.5 Apply Snell’s law together with geometric constraints.
Problem: A DVD is a video recording consisting of a spiral track about 1.0 μm wide with
digital information. The digital information consists of a series of pits that are “read” by a
laser beam sharply focused on a track in the information layer. If the width a of the beam
at the information layer must equal 1.0μm to distinguish individual tracks and the width
w
of the beam as it enters the plastic is 0.700 0 mm, find the angle θ
1
at which the conical
beam should enter the plastic. Assume the plastic has a thickness t=1.20 mm and an
index of refraction n=1.55. Note that this system is relatively immune to small dust
particles degrading the video quality because particles would have to be as large as 0.700
mm to obscure the beam at the point where it enters the plastic.
22.6 Calculate the consequences of dispersion:
Problem: A beam of light is incident on a prism of a certain glass at an angle of θ
1
= 30.0°,
as shown in Figure. If the index of refraction of the glass for violet light is 1.80, find (a) θ
2,
the angle of refraction at the airglass interface, (b) ϕ
1
, the angle of incidence at the glass
air interface,
and (c) ϕ
1
, the angle of refraction when the violet light exits the prism. (d)
What is the value of Δy, the amount by which the violet light is displaced vertically?
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 Summer '09
 Hinata
 Physics, Work, Light, Reflection And Refraction, Total internal reflection, Geometrical optics

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