Lesson 8.2.1

8.2.1 Thermionic emission and charged particles in accelerators Quiz: Pearson Edexcel Physics, Unit 8

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

In partnership with Revision Ninja

Lesson 8.2.1, Thermionic emission and charged particles in accelerators: 20 multiple choice questions for the Pearson Edexcel Physics (9PH0), Unit 8: Nuclear and Particle Physics, written with Revision Ninja.

Host it live on the board and students join with a game code on their own devices, or revise alone with Free Play. The answers are revealed in the game.

Host this setFree Play

The 20 questions

  1. What term describes the release of electrons from the surface of a heated metal?

    • Thermionic emission
    • Nuclear fission
    • Photoelectric effect
    • Field emission

  2. What process describes the emission of electrons from a heated metal surface?

    • Photoelectric effect
    • Field emission
    • Thermionic emission
    • Alpha decay

  3. What is the main purpose of drift tubes in a linear accelerator?

    • Shield electric fields
    • Increase particle mass
    • Accelerate charged particles
    • Focus particle beams

  4. What provides the centripetal force for charged particles inside a cyclotron?

    • Gravitational field
    • Electric field
    • Magnetic field
    • Strong force

  5. What accelerates charged particles as they cross the gap in a cyclotron?

    • Stationary magnetic field
    • Uniform magnetic field
    • Alternating electric field
    • Gravitational field

  6. What is the radius of the circular path of a charged particle of momentum p and charge Q in a magnetic field B?

    • r = p / (B Q^2)
    • r = BQ / p
    • r = p B / Q
    • r = p / (BQ)

  7. An electron leaves a hot cathode from rest and is accelerated through 2000 V. What is its speed? The electron mass is 9.11 x 10^-31 kg.

    • 2.7 x 10^7 m s^-1
    • 6.3 x 10^5 m s^-1
    • 1.9 x 10^7 m s^-1
    • 5.3 x 10^7 m s^-1

  8. An electron leaves a hot cathode from rest and is accelerated through 500 V. What kinetic energy does it gain, in joules?

    • 8.0 x 10^-17 J
    • 5.0 x 10^2 J
    • 3.1 x 10^-19 J
    • 8.0 x 10^-16 J

  9. A proton of mass 1.67 x 10^-27 kg moves at 1.0 x 10^6 m s^-1 perpendicular to a magnetic field of flux density 0.50 T. What is the radius of its path?

    • 2.1 x 10^2 m
    • 4.2 x 10^-2 m
    • 1.0 x 10^-2 m
    • 2.1 x 10^-2 m

  10. An electron moves in a circular path in a uniform magnetic field of flux density 0.10 T. What is the time for one complete revolution? The electron mass is 9.11 x 10^-31 kg.

    • 3.6 x 10^-8 s
    • 7.2 x 10^-10 s
    • 1.8 x 10^-10 s
    • 3.6 x 10^-10 s

  11. If the magnetic flux density in a cyclotron is doubled, the accelerating frequency must:

    • Remain unchanged
    • Quadruple
    • Halve
    • Double

  12. Why do drift tubes in a linear accelerator become progressively longer?

    • Magnetic force increases
    • Field frequency decreases
    • Particles gain mass
    • Particles speed up

  13. What equation gives the kinetic energy gained by charge Q accelerated across potential difference V?

    • Ek = V / Q
    • Ek = ½ QV²
    • Ek = QV
    • Ek = Q / V

  14. An electron of speed 5.0 x 10^6 m s^-1 enters a uniform magnetic field of flux density 0.020 T perpendicular to the field. What is the radius of its circular path?

    • 1.4 x 10^-3 m
    • 7.0 x 10^-4 m
    • 2.8 x 10^-3 m
    • 1.4 x 10^-6 m

  15. A proton and an alpha particle are accelerated from rest through the same potential difference and then enter the same uniform magnetic field perpendicular to it. What is the ratio of the alpha particle radius to the proton radius?

    • sqrt(2), about 1.4
    • 2.0
    • 0.50
    • 4.0

  16. Under what condition can particle mass be assumed constant in a cyclotron?

    • Speeds below c
    • Speeds near c
    • High particle mass
    • Zero magnetic field

  17. How do paths of oppositely charged particles differ when entering a magnetic field identically?

    • No deflection occurs
    • Opposite deflection directions
    • Parallel curved paths
    • Same deflection direction

  18. How do particle detectors use ionisation created by high-energy charged particles?

    • Absorbing particle charge
    • Halting particle motion
    • Tracing ion trails
    • Measuring particle mass

  19. A linear accelerator is driven by an alternating voltage of frequency 100 MHz. For how long is each half-cycle of the voltage?

    • 0.010 microseconds
    • 10 ns
    • 2.5 ns
    • 5.0 ns

  20. Why can a magnetic field alone not increase a particle's kinetic energy?

    • Opposes particle motion
    • Decreases particle speed
    • Does no work
    • Cancels electric fields

All Pearson Edexcel Physics quizzes