Conceptual Physics

Chapter Assumptions

1 eV = 1.60×10–19 J

h = 6.63×10–34 J·s

ƫ = 1.05×10–34 J·s

mec^2 = 0.511 MeV

Chapter 37 Problems

Conceptual Problems

C.1 Electron A is accelerated from rest by a potential difference of 500 volts, and electron B undergoes a similar treatment by a

potential difference of 1000 volts. Afterward, which electron has the larger de Broglie wavelength? Explain your answer.

Electron A Electron B

C.2 An electron and a proton are each accelerated from rest by a potential difference whose magnitude is 500 volts. (The

electron is accelerated from a potential of 0 V to 500 V, whereas the proton is accelerated from 500 volts to 0 volts.)

Afterward, which has the larger de Broglie wavelength? Explain your answer.

Electron Proton

C.3 A bowling ball is dropped from a tall building. While it is speeding up, does its de Broglie wavelength become smaller,

become larger, or stay the same? Explain your answer.

i. Becomes smaller

ii. Becomes larger

iii. Stays the same

Section Problems

Section 1 - The Compton effect

1.1 What is the momentum of a photon of visible light with wavelength 555 nm?

kg·m/s

1.2 What is the momentum of an x-ray photon with a frequency of 1.10e+18 Hz?

kg·m/s

Section 2 - Matter waves

2.1 What is the wavelength of a 1.20×10^3 kg car that is traveling along the highway at 99.0 km/hr?

m

2.2 The wavelength of a nonrelativistic electron is 2.71eí6 m. How fast is it moving? Express your answer as a fraction of the

speed of light, c.

c

2.3 The de Broglie wavelength of a particle is 7.01×10í^13 m and it is moving at 0.189% of the speed of light. What is its mass?

kg

2.4 The kinetic energy of an electron is 29.3 eV. (a) How fast is it moving, expressed as a fraction of the speed of light c? (b)

What is its wavelength?

(a) c(b) m

2.5 An electron, starting from rest, is accelerated through a potential difference and ends up with a de Broglie wavelength of

1.12×10í^10 m. What potential difference is needed to accomplish this?

V

2.6 An electron is moving such that its de Broglie wavelength equals the Compton wavelength. How fast is it moving, expressed

as a fraction of the speed of light c? Hint: You must use a relativistic expression for momentum.

c

(^696) Copyright 2000-2007 Kinetic Books Co. Chapter 37 Problems