Question

Select the following correct MC answer for the questions pertaining to the Photoelectric Experiment

1. The quantized nature of photon energy is confirmed by the photoelectric effect since

Select one:

a. only the right number of photons hitting the metal surface consecutively will cause electron ejection.

b. only a photon carrying the right amount energy will eject an electron from the metal surface.

c. only light of the highest intensity will be able to cause electron ejection.

d. any photon, regardless of the energy it carries, will be able to eject an electron.

2. In the photoelectric effect experiment we use a Hg lamp to shine a light on a metal surface encased inside a photocell. One of the things we observe is that the energy of electrons ejected from the metal surface is independent of the intensity of light that shines on that surface. In practice this means that

Select one:

a. if we don’t move the lamp at all the photoelectric effect cannot take place.

b. if we move the lamp further away from the photocell than the photocurrent (amount of ejected electrons) will increase.

c. if we move the lamp closer to the photocell nothing will happen to the photocurrent (amount of ejected electrons).

d. if we move the lamp closer to the photocell we will increase the photocurrent (amount of ejected electrons) without increasing individual electron’s energy.

3. In the photoelectric effect experiment we use a Hg lamp to shine a light on a metal surface encased inside a photocell. There are multiple filters mounted on the front of the photocell to help us separate the light from the lamp into single-wavelength beams. Which of the following statements is true?

Select one:

a. Knowing the wavelength of the incoming photons does not help us determine the energy of the ejected electrons.

b. Even if we had monochromatic light source, we would still need filters to separate its constituent wavelengths.

c. Without the filters the photoelectric effect cannot occur.

d. Without the filters the photoelectric effect will still happen, but we will have no way to determine which electron was ejected by which photon wavelength.

4. The sign (positive or negative) on the value of the work function gives us an indication of the direction of energy flow between the metal surface (the system) and the environment around it (the surroundings) during the photoelectric effect. The sign on the work function is interpreted from the point of view of the system (the metal surface). For example, if the work function is positive the energy is flowing into the system from the surroundings (i.e. the energy of the system is increasing). Which of the following statements is true?

Select one:

a. We expect the work function to be positive, because energy must be given to the system for an electron to be ejected.

b. We expect the work function to be positive, because energy must be released by the system for an electron to be ejected.

c. We expect the work function to be negative, because energy must be released by the system for an electron to be ejected.

d. We expect the work function to be negative, because energy must be given to the system for an electron to be ejected.

Answer 1

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