What is the photoelectric effect?

• Emission of light by electrons

• Emission of electrons when light shines on a metal

• Absorption of light by electrons

• Emission of X-rays by metals

What are the emitted electrons called in the photoelectric effect?

• Valence electrons

• Photoelectrons

• Cathode rays

• Alpha particles

According to classical wave theory, what determines whether electrons are ejected?

• Frequency of light

• Type of metal

• Intensity of light

• Wavelength only

What is the minimum frequency required to emit photoelectrons called?

• Peak frequency

• Work function

• Threshold frequency

• Critical wave

Which part of Einstein's explanation of the photoelectric effect contradicted classical theory?

• Energy is continuous

• Light acts as a wave

• Energy is transferred in photons

• Electrons are absorbed by light

What does the symbol 'hf' represent in Einstein's photoelectric equation?

• The kinetic energy of an electron

• The energy of a photon

• The work function of a metal

• The stopping voltage

What is the unit for measuring the work function (W)?

• Joules only

• Electron volts (eV)

• Newtons

• Amperes

What happens if the energy of a photon is less than the work function?

• An electron is always emitted

• The metal melts

• No photoelectron is emitted

• The electron speeds up

What does increasing the intensity of light do?

• Increases the energy of each photoelectron

• Increases the number of photoelectrons

• Decreases the threshold frequency

• Has no effect at all

What is the stopping voltage (Vs)?

• Voltage that attracts photoelectrons

• Voltage that removes electrons from the metal

• Minimum voltage needed to emit photoelectrons

• Voltage at which all photoelectrons are repelled