Photons

Q1. Electromagnetic radiation is transmitted in discrete packets of energy called ____, each with energy proportional to its ____.

Fill In Blanks · 2 points

• · photons
• · frequency
• · amplitude
• · waves
• · wavelength
• · electrons

Q2. Which of the following correctly gives the energy of a photon in terms of its frequency f and the Planck constant h?

Multiple Choice · 1 point

• · E = h/f
• · E = hf
• · E = hf²
• · E = f/h

Q3. A photon has a frequency of 6.0 × 10¹⁴ Hz. What is its energy? (h = 6.63 × 10⁻³⁴ J s)

Multiple Choice · 1 point

• · 1.11 × 10⁻⁴⁸ J
• · 3.98 × 10⁻¹⁹ J
• · 9.05 × 10⁻²⁰ J
• · 7.96 × 10⁻¹⁹ J

Q4. A photon has a wavelength of 500 nm. What is its energy? (h = 6.63 × 10⁻³⁴ J s, c = 3.0 × 10⁸ m s⁻¹)

Multiple Choice · 1 point

• · 1.99 × 10⁻²⁵ J
• · 7.96 × 10⁻¹⁹ J
• · 3.98 × 10⁻¹⁹ J
• · 9.95 × 10⁻²⁰ J

Q5. Which of the following correctly describes what happens during annihilation?

Multiple Choice · 1 point

• · A photon splits into a particle and its antiparticle
• · A particle collides with another particle of the same type to produce energy
• · A particle meets its corresponding antiparticle and both are converted into two photons
• · A high energy photon loses energy by emitting two lower energy photons

Q6. When an electron and a positron annihilate at rest, two photons are produced. Why must two photons be produced rather than one?

Multiple Choice · 1 point

• · One photon would carry too much energy for it to be stable
• · Conservation of momentum requires two photons travelling in opposite directions
• · Two photons are needed to conserve nucleon number
• · A single photon cannot carry the rest energy of two particles

Q7. An electron and positron annihilate at rest. Each has a rest energy of 0.511 MeV. What is the energy of each photon produced?

Multiple Choice · 1 point

• · 1.022 MeV
• · 0.511 MeV
• · 0.256 MeV
• · 2.044 MeV

Q8. Which of the following correctly describes pair production?

Multiple Choice · 1 point

• · Two photons combine to produce a single high energy photon
• · A single photon spontaneously converts into a particle and its corresponding antiparticle
• · A particle decays into two lower mass particles
• · Two particles annihilate to produce a pair of photons

Q9. What is the minimum photon energy required to produce an electron-positron pair? (rest energy of electron = 0.511 MeV)

Multiple Choice · 1 point

• · 0.511 MeV
• · 0.256 MeV
• · 2.044 MeV
• · 1.022 MeV

Q10. Put the following stages of pair production in the correct order.

Ordering · 1 point

• 1. A high energy photon travels through a region near a nucleus
• 2. The photon's energy is converted into mass, creating a particle-antiparticle pair
• 3. The electron and positron are produced travelling in opposite directions
• 4. If the positron subsequently meets another electron, annihilation occurs producing two photons