Q: A metal has a threshold frequency $$f_0 = 6.0$$ \times $$10^{14}$$\ \mathrm{Hz}$$. What is its work function in joules? (h = 6.63$$ \times $$10^{-34}$$\ \mathrm{J \cdot s}$$)

$$3.98 \times 10$$^{-19}$$\ \mathrm{J}$$

Question 1

Which of the following experimental observations from the photoelectric effect cannot be explained by classical wave theory of light?

Accepted Answer

The existence of a threshold frequency below which no electrons are emitted, regardless of light intensity.

Question 2

A metal surface has a work function $$\phi = 2.5\ \mathrm{eV}. $$What is the threshold wavelength $$\$$lambda_0$$ for this metal? (Use hc = 1240$$\ \mathrm{eV \cdot nm}$$)

Accepted Answer

$$\$$lambda_0$$ = 496\ \mathrm{nm}$$

Question 3

Which equation correctly relates the maximum kinetic energy of photoelectrons to the frequency of incident light and the threshold frequency?

Accepted Answer

$$KE_{max} = h(f - f_0$)$$

Question 4

If ultraviolet light of wavelength $$200\ \mathrm{nm} is $$incident on a metal with a work function $$\phi = 3.0\ \mathrm{eV}$$, what is the maximum kinetic energy of the emitted photoelectrons? ($$hc = 1240\ \mathrm{eV \cdot nm})$$

Accepted Answer

$$3.2\ \mathrm{eV}$$

Question 5

Which of the following statements best describes the effect of increasing the intensity of incident light (with frequency above threshold) on a metal surface in a photoelectric effect experiment?

Accepted Answer

The number of emitted photoelectrons increases, but their maximum kinetic energy remains unchanged.

Question 6

A photon has a wavelength of $$620\ \mathrm{nm}. $$What is its energy in electron volts? ($$hc = 1240\ \mathrm{eV \cdot nm})$$

Accepted Answer

$$2.0\ \mathrm{eV}$$

Question 7

Which of the following best defines the work function $$\phi of a $$metal?

Accepted Answer

The minimum energy required to remove an electron from the surface of the metal.

Question 8

In a photoelectric effect experiment, if the frequency of incident light is doubled (and is above the threshold frequency), what happens to the maximum kinetic energy of the emitted electrons?

Accepted Answer

It increases, but not necessarily doubles.

Question 9

Which of the following is the correct expression for the energy of a photon in terms of its wavelength $$\lambda$$?

Accepted Answer

$$E = \dfrac{hc}{\lambda}$$

Question 10

A metal has a threshold frequency $$f_0 = 6.0$$ 	imes $$10^{14}$$\ \mathrm{Hz}$$. What is its work function in joules? (h = 6.63$$ 	imes $$10^{-34}$$\ \mathrm{J \cdot s}$$)

Accepted Answer

$$3.98 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 11

Which of the following best explains why no photoelectrons are emitted when light of frequency below the threshold frequency is incident on a metal surface, regardless of intensity?

Accepted Answer

Each photon has energy less than the work function, so electrons cannot be emitted.

Question 12

If the work function of a metal is $$2.0\ \mathrm{eV}$$ and it is illuminated with light of wavelength $$400\ \mathrm{nm}$$, what is the maximum kinetic energy of the emitted electrons? ($$hc = 1240\ \mathrm{eV \cdot nm})$$

Accepted Answer

$$1.1\ \mathrm{eV}$$

Question 13

Which of the following statements is NOT a feature of the photoelectric effect as explained by Einstein's photon model?

Accepted Answer

The kinetic energy of emitted electrons depends on the intensity of the incident light.

Question 14

A photocell is illuminated with light of frequency $$f$$ such that $$f \u003e f_0$. If the intensity of the light is doubled, what happens to the number and maximum kinetic energy of the emitted photoelectrons?

Accepted Answer

The number increases, but the maximum kinetic energy remains the same.

Question 15

Which of the following is the correct definition of an electron volt (eV)?

Accepted Answer

The energy gained by an electron when it moves through a potential difference of 1 volt.

Question 16

In a photoelectric effect experiment, which parameter determines the maximum kinetic energy of the emitted electrons?

Accepted Answer

The frequency of the incident light.

Question 17

A metal has a work function $$\phi = 4.0\ \mathrm{eV}. $$What is the threshold frequency $$f_0$$ for this metal? ($$h = 6.63 	imes 10$$^{-34}$$\ \mathrm{J \cdot s}$$, $$1\ \mathrm{eV} = 1.6 	imes 10$$^{-19}$$\ \mathrm{J})$$

Accepted Answer

$$9.7 	imes 10$$^{14}$$\ \mathrm{Hz}$$

Question 18

Which of the following best describes the evidence for the photon nature of light from the photoelectric effect experiment?

Accepted Answer

Electrons are emitted only when the incident light has a frequency above a certain threshold, regardless of intensity.

The Photoelectric Effect: Concepts, Equations, and Applications

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