11 mark
The electric field patterns around three charged particles Q, R and S are shown. Which row in the table shows the charges on particles Q, R and S?
Forces on Charged Particles · Practice Test A
← Back to Higher practice testsNew page — if anything looks wrong or a mark scheme disagrees with your working, tell Mr Stewart.
Higher Physics · Forces on Charged Particles
Practice Test A
Answer everything, then mark it in one go.
25marks
35 minsuggested
10questions
Have your jotter and a pen beside you. Do every calculation in your jotter, showing the relationship, the substitution and the final answer with its unit, exactly as you would in the exam — this page asks you only for the relationship you used and your final answer.
Nothing is timed and nothing is sent anywhere — your answers stay on this device, so you can close the tab and come back.
Relationships you may need
| Quantity | Relationship |
|---|---|
| Work done moving a charge through a p.d. | Ew = QV |
| Kinetic energy | Ek = ½mv2 |
| Work done by a force | W = Fd |
| Force and acceleration | F = ma |
A charged particle accelerated from rest reaches a speed given by QV = ½mv2. That rearrangement is not on the relationships sheet — you are expected to derive it from these two lines.
Data sheet — the values this test needs
| Quantity | Symbol | Value |
|---|---|---|
| Magnitude of the charge on an electron | e | 1·60 × 10⁻¹⁹ C |
| Mass of electron | me | 9·11 × 10⁻³¹ kg |
| Mass of proton | mp | 1·673 × 10⁻²⁷ kg |
| Mass of alpha particle | mα | 6·645 × 10⁻²⁷ kg |
✏️ Working goes in your jotter. On this page you give the relationship and the final answer only — the mark scheme at the end shows the substitution you should have written down.
Warm-up
5 marksEveryone should aim for full marks here. One step, no rearranging.
21 mark
An electron enters a region of magnetic field as shown. The direction of the force exerted by the magnetic field on the electron as it enters the field is
31 mark
A charge of 2·5 × 10⁻⁶ C is moved through a potential difference of 60 V. The work done on the charge is
41 mark
A pupil makes the following statements about an electric field.
- A potential difference of 1 volt means 1 joule of work is done moving 1 coulomb of charge between two points.
- Electric field lines are drawn in the direction of the force on a positive charge.
- A negative charge released from rest moves in the same direction as the field lines.
51 mark
A linear accelerator uses hollow metal drift tubes in a vacuum. A pupil makes the following statements about it.
- The protons are accelerated in the gaps between the tubes.
- The supply alternates so that the field in each gap pushes the protons forwards every time they cross it.
- The tubes are made longer along the accelerator because the field inside a tube gets weaker.
Core
13 marksThe demand of the real test — one rearrangement, one conversion or one intermediate step.
65 marks
Inside an X-ray tube, electrons are released from rest at a heated cathode and accelerated through a vacuum towards the anode. The potential difference between the cathode and the anode is 4·5 kV.
(a) Explain why the electron accelerates towards the anode.2
(b) Calculate the work done on one electron as it accelerates from the cathode to the anode.3
75 marks
A cyclotron is used to produce isotopes for medical imaging. It has two hollow D-shaped electrodes, called dees, in a vacuum. Protons are released from rest at R and accelerated across the gap between the dees by a potential difference of 19·0 kV.
(a) Calculate the work done on a proton as it crosses the gap from R to S.2
(b) Determine the speed of the proton as it reaches S.3
83 marks
A narrow beam of electrons is directed from left to right into a region of uniform magnetic field between two coils. The path taken by the electrons is shown.
(a) Determine the direction of the uniform magnetic field.1
(b) The current in the coils is now increased. State the effect this has on the path of the electron beam, and justify your answer.2
Push
7 marksTwo or more steps, an unfamiliar context, and a judgement to justify.
95 marks
In a linear accelerator, protons are accelerated across the gap between two drift tubes by a potential difference of 28 kV. A proton is already travelling at 1·8 × 10⁶ m s⁻¹ when it reaches R.
(a) Calculate the work done on the proton as it accelerates from R to S.2
(b) Determine the speed of the proton as it reaches S.3
102 marks
The same linear accelerator is now used to accelerate alpha particles instead of protons, across the same gap and with the same accelerating potential difference. An alpha particle carries a charge of +2e.
State the effect this has on the kinetic energy gained by a particle crossing the gap, and justify your answer.
Your result
0out of 25
0%percentage
—indicative band
Bands are indicative only — they are a guide to where you are, not a grade.
Sources & credits: questions are adapted from Higher Physics past papers, reproduced and adapted for educational use — past papers and marking instructions © Qualifications Scotland (SQA). Numbers, particles and contexts have been changed, and one question is original to this site. Field and accelerator diagrams drawn for this site © R Stewart, 2026.