Conceptual Physics

Chapter Assumptions

Unless stated otherwise, use the following indices of refraction

nair = 1.00

nwater = 1.33

nglass = 1.50

Chapter 34 Problems

Conceptual Problems

C.1 Two beams of light, initially in phase, follow

the paths shown. In terms of the wavelength Ȝ,

what is the minimum length d that will result in

complete constructive interference between

the two beams?

Ȝ/6 Ȝ/3 Ȝ/2 3 Ȝ/4

C.2 In a single-slit diffraction pattern, when destructive interference occurs at a dark fringe, does this mean energy has been lost

from the light wave? Explain your answer.

Yes No

C.3 Two beams of light, initially in phase, follow

the paths shown. In terms of the wavelength Ȝ,

what is the minimum length d that will result in

complete destructive interference between the

two beams?

4 Ȝ Ȝ/8 Ȝ/4 3 Ȝ/2

C.4 In the old days before cable television, everyone received broadcast television signals by using an antenna perched on the

television or on the roof. You might think that if you had a clear line of sight to a nearby broadcasting station, you would

always receive a strong signal, but this is not true. Explain why the presence of surrounding buildings, which do not block the

signal but do reflect some of it, might reduce the signal received at a television antenna with a clear line of sight.

C.5 In recent years, cancer researchers have proposed a new way of treating previously inoperable brain tumors. Some

malignant tumors can be destroyed by focusing a narrow, high-energy x-ray beam on them. The beam must have a high

power, but at high intensities, a single beam will destroy healthy tissue in the path to the tumor. At lower powers, a single

beam will keep the healthy cells alive, but it will not kill the cancer cells. In order for the treatment to be effective, a tumor must

receive a full concentration of energy at one instant in time, but healthy cells must never receive the full concentration. How

can this be done?

Section Problems

Section 3 - Michelson interferometer

3.1 You are using a Michelson interferometer to measure the wavelength of the orange-red emission line in the spectrum of the

krypton-86 atom. When the movable mirror is shifted by a distance of 303 nm, the interference between the two beams moves

from constructive to destructive back to constructive. To three significant digits, what is the wavelength of this emission line?

m

(^636) Copyright 2000-2007 Kinetic Books Co. Chapter 34 Problems