Unit 9 Modern Physics Review

What is the definition of work function?

• The work function is the minimum energy needed to remove an electron from a material's surface.

• The work function is the energy required to heat a material.

• The work function is the energy needed to create a photon from a material.

• The work function is the total energy of an electron in a material.

Explain the photoelectric effect.

• The photoelectric effect is the reflection of light off a surface, causing electrons to be emitted.

• The photoelectric effect is the absorption of light by a material without any electron emission.

• The photoelectric effect occurs only in metals when exposed to ultraviolet light.

• The photoelectric effect is the emission of electrons from a material when it is exposed to light, demonstrating the particle nature of light.

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Define threshold frequency in the context of the photoelectric effect.

• The threshold frequency is the minimum frequency of light needed to initiate the photoelectric effect.

• The threshold frequency is the frequency of light that can only heat a material without causing electron emission.

• The threshold frequency is the frequency at which electrons are emitted regardless of light intensity.

• The threshold frequency is the maximum frequency of light that can cause the photoelectric effect.

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A particle of light is called a...

• Photoelectron

• Photon

• Proton

• Electron

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The only way to increase the number of photoelectrons emitted is by increasing the _________ of the light

• Intensity

• Wavelength

• Frequency

• Energy

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The energy of photoelectrons emitted from a metal surface can be increased by

• using light of higher frequency.

• using light of longer wavelength.

• using light of higher intensity.

• using monochromatic, polarized light.

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NGSS.HS-PS4-4

What is the best description of 'threshold frequency'?

• The minimum energy needed for electrons to escape a surface.

• The maximum kinetic energy that an emitted electron has.

• The minimum frequency of a photon that will cause an electron to be emitted.

• The frequency that an emitted electron will have.

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If the brightness of a beam of light increases without changing its color, the ______ will increase.

• number of photons

• frequency of the light

• energy of the photons

• wavelength of the photons

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The energy of a photon is directly proportional to its _____ and inversely proportional to its ______.

• intensity - speed

• wavelength - frequency

• frequency - wavelength

• intensity - wavelength

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A metal with a work function of 3.5 eV is exposed to photons with an energy of 3.7 eV. What is the maximum kinetic energy of the emitted photoelectrons?

• 0.2 eV

• 0.9 eV

• 1.1 eV

• 7.7 eV

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