Chapter 31: Properties of light

Chapter 31: Properties of light Section 31-1: The Speed of Light, and Concept Check 31-1

You are attempting to reproduce Fizeau’s determination of the speed of light. Using a wheel that has 720 teeth, light is observed when the wheel rotates and light is reflected between the teeth from a distant mirror. You assume that the time taken for the light to travel from the wheel to the mirror and back is the time for the wheel to rotate 1/720 of a revolution. You obtain a result for the speed of light which is 7 percent too low. What is the most likely source of error to account for this discrepancy? • You have miscounted the teeth. • You have not measured the angular speed correctly. • There are 720 teeth, but there are also 720 gaps, so the width of a tooth is less than 1/720 of the circumference of the wheel. • You have not measured the distance to the mirror correctly. • Light travels 7% slower in air than in a vacuum.

Mission Control sends a brief wake-up call to astronauts in a distant spaceship. Five seconds after the call is sent, Mission Control hears the waking groans of the astronauts. How far away (at most) from the earth is the spaceship? • 7.5 ×108 m • 15 × 108 m • 30 × 108 m • 45 × 108 m • There is no upper limit on the distance.

The speed of ultraviolet radiation in free space compared with the speed of visible radiation in free space is • greater. • the same. • less.

The speed of radio waves in free space compared with the speed of visible radiation in free space is • greater. • the same. • less.

Ultra fast pulse lasers can emit pulses of the order 10 fs. The physical length of each pulse that is 10 fs long in duration is • 1.0 μm • 2.0 μm • 3.0 μm • 9.0 μm • 12.0 μm

Chapter 31: Properties of light Section 31-3: Reflection and Refraction

As light passes from one medium into another, the angle of refraction is smaller in the medium with the _____ index of refraction and _____ speed of light. • larger; lower • larger; higher • smaller; lower • smaller; higher

A glass block with index of refraction 1.50 is immersed in water whose index of refraction is 1.33. The critical angle at the glass–water interface is • 6.5º • 41.9º • 48.8º • 56.3º • 62.5º

Which of the following statements is true about the speeds of the various colors of light in glass? • All colors of light have the same speed in glass. • Violet has the highest speed, red the lowest. • Red has the highest speed, violet the lowest.

A light wave traveling at speed v1 in medium 1 passes into medium 2 where its speed is v2. By which of the following equations is the frequency f1 of the wave in medium 1 related to its frequency f2 in medium 2? • f1v2 = f2v1 • f1 = f2 • f1v1 = f2v2

Light that has been traveling in a medium with an index of refraction n2 is incident on the boundary surface of another medium with an index of refraction n1. Given a sufficient angle of incidence, which of the following conditions must be satisfied for total internal reflection to occur? • n1 < n2 • n1 > n2 • n1 = n2

You are trying to catch fish by using a spear. You observe a large fish a couple of meters in front of you and a meter below the water surface. In order to hit the fish with your spear you must aim (assume that the fish is stationary and does not swim away in fright) • directly at the point where you see the fish. • slightly above the point where you see the fish. • slightly below the point where you see the fish.

You see a fish in water at an apparent depth of 1.83 m. The actual depth of the fish, if the index of refraction of the water relative to air is 4/3, must be • 3.81 cm • 61.0 cm • 1.37 m • 1.83 m • 2.44 m

A ray of light passes from air into water, striking the surface of the water with an angle of incidence of 45º. Which of the following four quantities change as the light enters the water: (1) wavelength, (2) frequency, (3) speed of propagation, and (4) direction of propagation? • 1 and 2 only • 2, 3, and 4 only • 1, 3, and 4 only • 3 and 4 only • 1, 2, 3, and 4

A light ray makes an angle of 42º with the normal to a glass-water surface on the glass side of the surface. The angle q in the water is • 42º • 36º • 63º • 49º • 27º

In the laboratory you used the spectrometer to determine the indices of refraction of various wavelengths of light. Which curve could represent a plot of the index of refraction as a function of the wavelength of the light?

Monochromatic light is incident on the prism at the proper angle for minimum deviation. The emergent ray passes through which point?

Light travels in a medium of index of refraction n', passes into a medium of index n", where n" > n', and then into air, where nair < n' < n". Which ray correctly shows the light path?

Light from an underwater source at O impinges upon a water-air interface. Which label shows the critical angle?

The light ray that passes through the prism and emerges at the angle of minimum deviation for that color is • red • yellow • green • blue • violet

An air prism is immersed in water. A ray of monochromatic light strikes one face as shown. Which arrow shows the emerging ray?

Which label shows the angle of minimum deviation?

The figure shows the electric field strength versus distance for light that is normally incident on and transmitted through a refractive medium. The index of refraction of this medium is • 1.0 • 1.5 • 2.0 • 0.67 • 3.0

A ray of light in glass is incident on a glass–air interface as shown. You would expect a ray to pass through • point 1 only. • point 3 only. • point 4 only. • points 2 and 4. • points 1 and 4.

The rays in the figure are reflected and refracted at the front and back surfaces of the glass. Which of the following is true of the angles of these rays relative to normal? • 1 = 2 = 3 = 4 • 1 = 2; 3 = 4; but 1 ≠ 3 • 1 = 2 = 3; but 4 ≠ 1 • 1 = 4; but 2 ≠ 4 • 1 ≠ 2 ≠ 3 ≠ 4

Chapter 31: Properties of light