4.5.1 Photoelectric Effect

• Higher frequency of light increases the kinetic energy of emitted electrons but does not affect their number
• Einstein's theory states light consists of discrete packets of energy called photons
• In Einstein's theory, electrons are ejected only if the photon's energy exceeds the metal's work function
• The light source in the photoelectric effect experimental setup provides light of varying frequency and intensity
• What did Einstein's theory postulate about the nature of light?

  Discrete packets of energy
• The classical wave theory could explain the immediate emission of electrons in the photoelectric effect.

  False
• The maximum kinetic energy of ejected electrons is given by $K.E.\max =$$hf - Φ$
• In the photoelectric effect, electrons are ejected only when photon energy equals or exceeds the work function
• Einstein's theory resolved contradictions in classical wave theory regarding the photoelectric effect.


  True
• The kinetic energy of emitted electrons depends on the light intensity in the photoelectric effect.

  False
• The intensity of light affects the kinetic energy of emitted electrons.

  False
• Match the component with its function:

  Voltmeter ↔️ Measures stopping potential

  Ammeter ↔️ Measures electric current
• Electrons are ejected if the photon's energy is less than the work function of the metal.

  False
• What is the formula for the maximum kinetic energy of emitted electrons, according to Einstein's theory?

  $K.E.\max =$$hf - Φ$
• Steps in Einstein's explanation of the photoelectric effect

  1️⃣ Light is quantized into photons

  2️⃣ Electrons are ejected if photon energy exceeds the work function

  3️⃣ Excess photon energy becomes electron kinetic energy
• What did Einstein's theory provide strong support for regarding the nature of light?

  Particle nature
• The threshold frequency is the minimum frequency needed for electron emission


  True
• What is the numerical value of Planck's constant?

  6.626 x 10^-34 Js
• How do digital cameras use the photoelectric effect to capture images?

  Record photon intensity
• Different metals have the same work function in the photoelectric effect.

  False
• Light energy is quantized according to Einstein's theory.


  True
• How does higher intensity of light affect electron emission in the photoelectric effect?

  More electrons are emitted
• Einstein's theory states that light consists of discrete packets of energy called photons
• Steps in the photoelectric effect according to Einstein's theory

  1️⃣ Light composed of photons strikes metal surface

  2️⃣ Electrons are ejected if photon energy equals or exceeds the work function

  3️⃣ Excess photon energy becomes kinetic energy of ejected electrons
• A threshold frequency is required for electron ejection in the classical wave theory.

  False
• What depends on the frequency of light, according to the photoelectric effect?

  Kinetic energy
• What is the threshold frequency (f₀) in the photoelectric effect?

  Minimum frequency for emission
• What is the photoelectric effect defined as?

  Emission of electrons from light
• What affects the minimum energy required to eject an electron from a metal surface?

  Work function
• What are the discrete packets of energy in light called, according to Einstein's theory?

  Photons
• What does the maximum kinetic energy of emitted electrons depend on, according to Einstein's theory?

  Photon frequency
• The energy of a photon is given by E = hf
• Electrons are ejected only if the photon's energy equals or exceeds the work function
• The quantization of light means it exists as discrete packets of energy called photons
• Match the characteristic with the correct theory

  Threshold Frequency Required ↔️ Photoelectric Effect

  Kinetic Energy Depends on Intensity ↔️ Classical Wave Theory
• Light with a frequency of 2 x 10^15 Hz has an energy of 13.252 x 10^-19 J


  True
• What is the photoelectric effect?

  Emission of electrons by light
• Match the experimental component with its role:

  Light Source ↔️ Provides light of varying frequency and intensity

  Photocell ↔️ Contains a metal surface and electrodes

  Voltmeter ↔️ Measures the stopping potential

  Ammeter ↔️ Measures the electric current
• What is the formula for the maximum kinetic energy of emitted electrons in the photoelectric effect?

  $K.E._{\max} =$$hf - \Phi$
• Higher frequency of light affects the number of emitted electrons.

  False