现代物理学 知到智慧树答案满分完整版章节测试

第一章 单元测试

1、单选题：
As a high-speed spaceship flies past you, it fires a strobe light that sends out a pulse of light in all directions. An observer aboard the spaceship measures a spherical wave front that spreads away from the spaceship with the same speed in all directions. What is the shape of the wave front that you measure? （ ）

A:ellipsoidal, with the longest axis of the ellipsoid along the direction of the spaceship’s motion;
B:spherical
C:ellipsoidal, with the shortest axis of the ellipsoid along the direction of the spaceship’s motion
D:not enough information is given to decide.
答案: spherical

2、单选题：
Stanley, who works for the rail system, has carefully synchronized the clocks at all of the rail stations. At the moment that Stanley measures all of the clocks striking noon, Mavis is on a high-speed passenger car traveling from Ogdenville toward North Haverbrook. According to Mavis, when the Ogdenville clock strikes noon, what time is it in North Haverbrook?（ ）

A:noon
B:before noon
C:after noon
D:not enough information is given to decide
答案: after noon

3、单选题：
Samir (who is standing on the ground) starts his stopwatch at the instant that Maria flies past him in her spaceship at a speed of 0.600c. At the same instant, Maria starts her stopwatch. As measured in Samir’s frame of reference, what is the reading on Maria’s stopwatch at the instant that Samir’s stopwatch reads 10.0 s? （ ）

A:less than 10.0 s
B:not enough information is given to decide
C:more than 10.0 s
D:10.0 s
答案: less than 10.0 s

4、判断题：
In frame S events P1 and P2 occur at the same x-, y- and z-coordinates, but event P1 occurs before event P2. In frame S’, event P1 occurs first。（ ）

A:对
B:错
答案: 对

5、单选题：
According to relativistic mechanics, when you double the speed of a particle, the magnitude of its momentum increases by （ ）

A:a factor between 1 and 2 that depends on the mass of the particle
B:a factor smaller than 1
C:a factor of 2
D:a factor greater than 2
答案: a factor greater than 2

第二章 单元测试

1、多选题：
Silicon films become better electrical conductors when illuminated by photons with energies of 1.14 eV or greater, an effect called photoconductivity. Which of the following wavelengths of electromagnetic radiation can cause photoconductivity in silicon films?（ ）

A:infrared light with λ = 1200 nm
B:red light with λ = 600 nm
C:ultraviolet light with λ = 300 nm
答案: red light with λ = 600 nm;
ultraviolet light with λ = 300 nm

2、单选题：
In the apparatus used to produce x rays, similar to Röntgen’s 1895 apparatus, suppose you increase the number of electrons that are emitted from the cathode per second while keeping the potential difference VAC the same. How will this affect the intensity I and minimum wavelength λmin of the emitted x rays? （ ）

A:I will increase but λmin will decrease
B:I will increase but λmin will be unchanged
C:I and λmin will both increase
D:I will remain the same but λmin will decrease
E:none of these
答案: I will increase but λmin will be unchanged

3、判断题：
If you used visible-light photons in the Compton-effect experiment, the photons would undergo a wavelength shift due to the scattering.（ ）

A:错
B:对
答案: 对

4、判断题：
If you used visible-light photons in the Compton-effect experiment, it is possible to detect the shift with the human eye。（ ）

A:错
B:对
答案: 错

5、单选题：
Through which of the following angles is a photon of wavelength λ most likely to be deflected after passing through a slit of width a? Assume that is much less than a. （ ）

A:θ=2λ/a
B:θ=3λ/2a
C:not enough information given to decide
D:θ=3λ/a
E:θ=λ/a
答案: θ=3λ/2a

第三章 单元测试

1、单选题：
A proton has a slightly smaller mass than a neutron. Compared to the neutron, would a proton of the same wavelength have （ ） ?（ ）

A:less kinetic energy
B:the same kinetic energy
C:more kinetic energy
答案: more kinetic energy

2、单选题：
Suppose you repeated Rutherford’s scattering experiment using a thin sheet of solid hydrogen in place of the gold foil. (Hydrogen is a solid at temperatures below 14.0 K.) The nucleus of a hydrogenatom is a single proton, with about one-fourth the mass of an alpha particle. Compared tothe original experiment with gold foil, would you expect the alpha particles in this experimentto undergo（ ）？ （ ）

A:the same amount of large-angle scattering
B:more large-angle scattering
C:less large-angle scattering
答案: less large-angle scattering

3、单选题：
Consider the possible transitions between energy levels in a He+ ion. For which of these transitions in He+ will the wavelength of the emitted photon be nearly the same as one of the wavelengths emitted by excited H atoms？（ ）

A:more than one of these
B:n = 4 to n = 3
C:none of these
D:n = 3 to n = 2
E:n = 2 to n = 1
答案: more than one of these

4、单选题：
An ordinary neon light fixture like those used in advertising signs emits red light of wavelength 632.8 nm. Neon atoms are also used in a helium–neon laser (a type of gas laser). The light emitted by a neon light fixture is （ ）

A:stimulated emission
B:spontaneous emission
C:both spontaneous and stimulated emission
答案: spontaneous emission

5、判断题：
A blackbody at 2000 K emits x rays and it also emits radio waves.（ ）

A:对
B:错
答案: 对