quantum physics

• What phenomenon is demonstrated by Young's double-slit experiment?

  Interference pattern of light
• Why does light create an interference pattern in Young's double-slit experiment?

  Because light acts like a wave
• What is one main piece of evidence for the wave nature of light?

  Diffraction
• What effect shows that light can act like a particle?

  Photoelectric effect
• What happens when electrons are fired through small gaps?

  They exhibit diffraction patterns
• What size gaps are necessary for electron diffraction to occur?

  On the order of atomic size
• What is observed on the screen when electrons pass through a thin metal foil?

  Concentric circular diffraction pattern
• What does the circular diffraction pattern indicate about electrons?

  Electrons behave like waves
• Who first suggested the concept of matter wavelength for particles?

  Louis de Broglie
• What is the formula relating velocity, frequency, and wavelength?

  V = F * λ
• Why can't the formula V = F * λ be used for particles?

  Speed doesn't affect frequency and wavelength
• What is the formula for momentum of a particle?

  P = m * v
• What is the relationship between mass, velocity, and de Broglie wavelength?

  Wavelength is inversely proportional to mass
• Why do larger particles not exhibit noticeable diffraction?

  Their wavelengths are too small
• What happens to the wavelength of a particle if it moves too fast?

  The wavelength becomes too small
• What is the purpose of an electron gun?

  To accelerate electrons
• What is the role of the cathode in an electron gun?

  It emits electrons
• What does the anode do in an electron gun?

  Accelerates electrons through a gap
• What is the formula for energy in terms of voltage and charge?

  E = V * Q
• What type of energy is given to an electron after being accelerated?

  Kinetic energy
• What is the formula for kinetic energy of an electron?

  KE = 1/2 mv²
• How do you find the speed of an electron after acceleration?

  Rearrange KE = 1/2 mv²
• What is the relationship between accelerating voltage and electron speed?

  Higher voltage increases electron speed
• What is the significance of the mass of an electron in calculating wavelength?

  It determines the de Broglie wavelength
• What are the key concepts of electron diffraction and de Broglie wavelength?

  • Electrons exhibit wave-like behavior
  • Diffraction occurs through small gaps
  • Circular patterns indicate wave properties
  • De Broglie wavelength relates to particle momentum
  • Wavelength inversely proportional to mass
• How do you calculate the wavelength of an electron?

  1. Determine the speed using KE = 1/2 mv²
  2. Use de Broglie wavelength formula: λ = h/p

  • Where h = Planck's constant
  • p = momentum (mv)
• What are the conditions for observing electron diffraction?

  • Electrons must pass through very small gaps
  • Gaps must be on the order of atomic size
  • Electrons should not be moving too fast
• What two things does the photoelectric effect involve?

  Light and electrons
• What does the photoelectric effect prove about light?

  Light acts as a particle
• Who was the first to propose a quantum theory of light?

  Isaac Newton
• What did Newton think light traveled in?

  Little packets called corpuscles
• Who proposed that light acts like a wave?

  Christiaan Huygens
• What are the discrete packets of energy called?

  Photons
• What is the formula for the energy of one photon?

  Energy = HF
• What is Planck's constant value?

  $6.63 \times 10^{-34} \text{ J s}$
• Who revived Newton's particle theory of light?

  Albert Einstein
• What happens when light shines on a piece of metal?

  Electrons are liberated from the metal
• What is the relationship between light intensity and electron kinetic energy?

  Higher intensity does not increase kinetic energy
• What is the stopping potential?

  Voltage to stop electrons from reaching the plate
• How is the kinetic energy of electrons measured?

  By using the stopping potential