Question 1

What advantage might an electron microscope have over a light microscope?

Accepted Answer

Electron microscopes use electron beams with shorter wavelengths than visible light, allowing for higher resolution and magnification.

Question 2

A proton and an electron are both accelerated to the same final speed. If λ_p is the de Broglie wavelength of the proton and λ_e is the de Broglie wavelength of the electron, then

Accepted Answer

The answer of A proton and an electron are both...

Question 3

A proton and an electron are both accelerated to the same final kinetic energy. If λ_p is the de Broglie wavelength of the proton and λ₃ is the de Broglie wavelength of the electron, then

Accepted Answer

The de Broglie wavelength is inversely proportional to the momentum. Since the proton is much more massive than the electron, for the same kinetic energy, the proton will have a smaller velocity and thus a larger momentum, resulting in a shorter wavelength compared to the electron.

Question 4

In a Compton scattering experiment, what scattering angle produces the greatest change in wavelength?

Accepted Answer

The greatest change in wavelength during Compton scattering occurs at a scattering angle of 180°, where the photon is scattered directly backward.

Question 5

The Compton effect demonstrates

Accepted Answer

The Compton effect demonstrates that light acts as photons, that the relativistic formulation works well, and that there is a consistent explanation for the scattered photon shift in wavelength.

Question 6

A beam of red light and a beam of violet light each deliver the same power on a surface. For which beam is the number of photons hitting the surface per second the greatest?

Accepted Answer

Red light has a longer wavelength and therefore lower energy per photon compared to violet light. To deliver the same power, the red beam must have more photons per second.

Question 7

Photons of visible wavelengths are shone on a surface starting with one end of the spectrum and gradually proceeding to the other end. When 589 nm is reached, electrons start coming out of the surface. Which of the following is true?

Accepted Answer

The wavelength of 589 nm corresponds to the yellow region of the visible spectrum, which is closer to the red end. Since electrons start being ejected at this wavelength, it indicates that the scan started from the red end, as shorter wavelengths (towards blue) have higher energy.

Question 8

You perform Compton scattering experiments with X-rays of a fixed wavelength. In one experiment you scatter the X-rays from free electrons. In the second experiment you scatter the X-rays from protons instead. For X-rays scattered under a given angle, the wavelength change

Accepted Answer

The answer of You perform Compton scattering experiments with X-rays...

Question 9

In the non-relativistic case, doubling the speed of an electron causes its wavelength to

Accepted Answer

In the non-relativistic case, the wavelength of an electron is inversely proportional to its momentum (and hence its speed) according to the de Broglie equation. Doubling the speed halves the wavelength.

Question 10

What scattering angle in the Compton effect produces the minimum change in frequency?

Accepted Answer

The minimum change in frequency occurs when the scattering angle is 0° (when the photon is scattered back in the direction it came from) because this gives the minimum amount of momentum transfer to the electron.

Question 11

In the Compton effect, if a photon is scattered at a particular angle, the resulting shift in wavelength for the scattered photon

Accepted Answer

The shift in wavelength in the Compton effect depends only on the scattering angle and is independent of the incident photon's energy or wavelength.

Question 12

In the relativistic case, doubling the speed of an electron causes its wavelength to

Accepted Answer

In the relativistic case, as the speed of an electron approaches the speed of light, its relativistic mass increases, causing its wavelength to decrease more than proportionally. Thus, doubling the speed results in a wavelength decrease to less than one-half.

Question 13

When a proton passes through matter, it is possible for it to interact with the matter in such a way that an electron and a positron are produced; this interaction is referred to as

Accepted Answer

Pair production is the process where a photon or high-energy particle interacts with matter to produce an electron and a positron.

Question 14

A source of light is at a temperature of 1000°C. Its temperature is then increased to 2000°C, Increasing the temperature causes the peak intensity wavelength to

Accepted Answer

According to Wien's Law, the peak wavelength is inversely proportional to the temperature. Doubling the temperature will cause the peak wavelength to decrease, but not quite halve.

Question 15

As a result of Compton scattering, the scattered photon has

Accepted Answer

In Compton scattering, the scattered photon loses energy, resulting in an increase in its wavelength compared to the incident photon.

Question 16

A metal surface is illuminated with blue light and electrons are ejected at a given rate each with a certain amount of energy. If the intensity of the blue light is increased, electrons are ejected

Accepted Answer

Increasing the intensity of light increases the number of photons, thus increasing the rate of electron ejection, but the energy per electron depends on the frequency of the light, which remains unchanged.

Question 17

As a particle travels faster, its de Broglie wavelength

Accepted Answer

The de Broglie wavelength is inversely proportional to the particle's momentum. As the particle's speed increases, its momentum also increases, which in turn decreases its de Broglie wavelength.

Question 18

In order for a photon to eject an electron from a metal's surface in the photoelectric effect, the photon's

Accepted Answer

The photoelectric effect requires that the photon has a frequency greater than a certain threshold frequency to provide enough energy to overcome the work function of the metal and eject an electron.

Question 19

What happens to the frequency of the scattered X-rays as the scattering angle in the Compton effect decreases?

Accepted Answer

In the Compton effect, as the scattering angle decreases, the frequency of the scattered X-rays increases because the energy of the scattered photon is higher at smaller angles.

Question 20

Light of a given wavelength is used to illuminate the surface of a metal, however, no photoelectrons are emitted. In order to cause electrons to be ejected from the surface of this metal you should

Accepted Answer

The question describes the photoelectric effect, in which electrons are ejected from a metal's surface by the absorption of photons. The minimum energy required to eject an electron is determined by the work function of the metal, which is a characteristic property of the metal. If the energy of the photons (which is related to their wavelength) is less than the work function, no photoelectrons will be emitted. The only way to increase the energy of the photons is to use light of a shorter wavelength. Therefore, answer B is correct. Increasing the intensity of the light (choice C) will not overcome the energy threshold required for emission, and decreasing the intensity (choice D) will simply decrease the number of emitted electrons without affecting their energy. Using light of the same wavelength (choice A) will not change the energy of the photons, and thus will not lead to emission if the original wavelength was already below the work function.

Quiz 37: Early Quantum Theory and Models of the Atom