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Lesson: The Photoelectric Effect

In this lesson, we will learn how to relate electromagnetic radiation wavelength to the kinetic energy of electrons ejected by it from various materials.

Sample Question Videos

04:17

Worksheet • 20 Questions • 1 Video

Q1:

The work function of a photoelectrode is 4.73 eV. Find the maximum velocity of photoelectrons ejected from the photoelectrode by 80.0-nm radiation.

  • A 1 . 9 5 × 1 0 6 m/s
  • B 2 . 3 5 × 1 0 6 m/s
  • C 1 . 8 3 × 1 0 6 m/s
  • D 2 . 2 3 × 1 0 6 m/s
  • E 2 . 1 0 × 1 0 6 m/s

Q2:

Silver has a work function of 4.73 eV. What is the longest wavelength of radiation that can eject a photoelectron from silver?

Q3:

Ultraviolet radiation of wavelength 1 . 2 0 × 1 0 − 7 m illuminates a gold-plated electrode. What is the maximum kinetic energy of photoelectrons ejected from the electrode?

Q4:

Photons of wavelength’s greater than 337 nm cannot eject photoelectrons from a magnesium photoelectrode. What is the work function of magnesium?

Q5:

Electromagnetic radiation ejects 2.00-eV electrons from a calcium electrode that has a work function of 2.71 eV. What is the wavelength of the radiation?

Q6:

The work function of a metal is 3.20 eV. What is the longest wavelength photon that can eject a photoelectron from this metal surface?

Q7:

Photons with wavelengths longer than 304 nm cannot eject photoelectrons from an aluminium photoelectrode. Calculate the work function of aluminium.

  • A 4.09 eV
  • B 4.22 eV
  • C 3.93 eV
  • D 4.16 eV
  • E 4.00 eV

Q8:

A beam of 400-nm wavelength light emitted by a laser is projected onto a calcium electrode, causing photoelectrons to be ejected. The power of the laser beam is 2.00 mW and the work function of calcium is 2.31 eV.

How many photoelectrons per second are ejected?

  • A 4 . 0 2 × 1 0 1 5
  • B 4 . 2 3 × 1 0 1 5
  • C 3 . 9 5 × 1 0 1 5
  • D 4 . 1 6 × 1 0 1 5
  • E 4 . 1 0 × 1 0 1 5

What net power is carried away by the ejected photoelectrons?

Q9:

600-nm wavelength light falls on a photoelectric surface. Electrons with a maximum kinetic energy of 0.170 eV are emitted from the surface.

Determine the work function of the surface.

Determine the cutoff frequency of the surface.

What is the stopping potential when the surface is illuminated with light of wavelength 400 nm?

Q10:

The work function of calcium is 2.31 eV. A laser with a power output of 2.00 mW at a 400-nm wavelength is used to project a beam of light onto a calcium photoelectrode, causing photoelectrons to be ejected.

How many photoelectrons leave the calcium surface per second?

  • A 4 . 0 2 × 1 0 1 5
  • B 4 . 2 3 × 1 0 1 5
  • C 3 . 9 5 × 1 0 1 5
  • D 4 . 1 6 × 1 0 1 5
  • E 4 . 1 0 × 1 0 1 5

What power is carried away by the ejected photoelectrons?

Calculate the photocurrent provided by the ejected photoelectrons.

If the photoelectrode suddenly becomes electrically insulated and the setup of two electrodes in the circuit suddenly starts to act like a 2.00-pF capacitor, how long will a photelectric current be maintained before the capacitor voltage stops it?

Q11:

Find the wavelength of the radiation that can eject 0.210 eV electrons from a sodium electrode. Use a value of 2.29 eV for the work function of sodium.

Q12:

Photoelectrons are ejected from a photoelectrode. The work function of the photoelectrode is 1.67 eV and the incident radiation has a wavelength of 450 nm. What is the kinetic energy of the ejected photoelectrons?

Q13:

The cutoff wavelength for the emission of photoelectrons from a surface is 540 nm. Find the maximum kinetic energy of the ejected photoelectrons when the surface is illuminated with a light of wavelength 480 nm.

Q14:

Find the maximum kinetic energy of photoelectrons ejected from calcium by the incident radiation of wavelength 100 nm. Use a value of 4.30 eV for the work function of calcium.

Q15:

A 374 nm light ejects photoelectrons with a maximum kinetic energy of 0.960 eV from a sodium photoelectrode. What is the work function of sodium?

Q16:

Calculate the power of the ejected photoelectrons from a 2.35 mm2 area of calcium metal by 450 nm wavelength radiation with an intensity of 1.42 kW/m2.

  • A 3 . 3 4 × 1 0 − 3 W
  • B 4 . 3 3 × 1 0 − 3 W
  • C 1 . 5 0 × 1 0 − 3 W
  • D 1 . 4 5 × 1 0 − 3 W
  • E 6 . 3 9 × 1 0 − 3 W

Q17:

The work function of a photoelectric surface is 1.40 eV. What is the maximum speed of the photoelectrons emitted from this surface when 500 nm wavelength light falls on it?

Q18:

Find the longest wavelength of light that can eject a photoelectron from zinc. Use a value of 4.30 eV for the work function of zinc.

Q19:

The cutoff wavelength for the emission of photoelectrons from a surface is 470 nm. The surface is illuminated with light of wavelength 570 nm. By how much does the energy of the incident photons fall short of the minimum energy required to eject a photoelectron?

Q20:

The calcium used in a photoelectrode has a work function of 2.90 eV.

What is the photoelectrode’s cutoff frequency?

What is the stopping potential for the emitted electrons when this photoelectrode is exposed to radiation of frequency 1 3 5 0 THz?
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