Quantum

• What is the stopping potential in the photoelectric effect?

  The minimum potential difference required to stop the electrons from leaving the metal plate
• What does the photoelectric effect demonstrate about light?

  It proves that light acts as a particle
• What is a photon?

  A discrete packet of energy
• What is the formula for the energy of a photon?


  € = h \cdot f
• What is Planck's constant?

  6.63 × 10^{-34} \text{ J s}
• What is the threshold frequency?

  The minimum frequency of photons required to liberate electrons from the surface of a metal plate
• What is the work function in the context of the photoelectric effect?

  The minimum energy required to remove an electron from the surface of a metal
• How is the stopping potential related to the kinetic energy of liberated electrons?

  The stopping potential is equal to the kinetic energy of the electrons
• If the stopping potential is represented as $V_s$, what is the equation relating it to kinetic energy?


  $E_k =$$eV_s$
• What happens when the intensity of light is increased in the photoelectric effect?

  Increasing intensity does not increase the energy of individual photons
• What is the relationship between energy and frequency of a photon?

  The energy of a photon is directly proportional to its frequency
• What occurs when an electron absorbs a photon?

  The electron can become excited and move to a higher energy level
• What happens when an electron returns to its original energy level after excitation?

  It emits a photon
• What is ionization in the context of atomic structure?

  Ionization occurs when an atom loses an orbital electron and becomes charged
• What is the ground state of an electron?

  The most stable energy level an electron can exist in
• How do you calculate the wavelength of a photon?


  $\lambda =$$\frac{c}{f}$
• What happens if the energy of a photon is less than the threshold energy?

  The photon is not absorbed by the electron
• What is the process of excitation in atoms?

  • An electron absorbs a photon
  • The electron moves to a higher energy level
  • If the electron returns to its original level, it emits a photon
• What are the characteristics of absorption and emission spectra?

  • Absorption spectra:
  • Frequencies/wavelengths absorbed by electrons
  • Electrons collide with atoms and get excited
  • Emission spectra:
  • Frequencies/wavelengths emitted as electrons return to ground state
  • More lines appear due to multiple routes back to ground state
• What gas is used in a fluorescent tube?

  Low pressure mercury gas
• What happens when electrons collide with mercury atoms in a fluorescent tube?

  The electrons are excited and emit UV photons
• What is the result of UV photons being absorbed by the coating in a fluorescent tube?

  It emits visible light photons
• Why do you expect more lines on the emission spectrum of a fluorescent tube?

  Electrons can take multiple routes back to the ground state