11 mark
Two parallel metal plates X and Y are connected to a supply. The electric field between them is shown. An electron is placed at rest at the point P, half-way between the plates. Which row in the table is correct?
Forces on Charged Particles · Practice Test B
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Higher Physics · Forces on Charged Particles
Practice Test B
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 alpha particle enters a region of magnetic field as shown. The direction of the force exerted by the magnetic field on the alpha particle as it enters the field is
31 mark
A charge of 8·0 × 10⁻⁶ C is moved between two points in an electric field. The work done on the charge is 3·6 × 10⁻³ J. The potential difference between the two points is
41 mark
A pupil makes the following statements about magnetic fields.
- A moving charge produces a magnetic field around it.
- Dots drawn on a diagram show a magnetic field directed into the page.
- The force on a charged particle moving through a magnetic field is at right angles to both the field and the particle's direction of travel.
51 mark
A pupil makes the following statements about a cyclotron.
- The protons are accelerated by the electric field in the gap between the dees, not by the magnetic field.
- The voltage alternates so that the proton is given a forward push every time it crosses the gap.
- The radius of the proton's path inside a dee decreases as the proton gains speed.
Core
13 marksThe demand of the real test — one rearrangement, one conversion or one intermediate step.
65 marks
Alpha particles are released from rest at plate A and accelerated in a vacuum towards plate B. The potential difference between the plates is 3·20 kV. An alpha particle carries a charge of +2e and has a mass of 6·645 × 10⁻²⁷ kg.
(a) Calculate the work done on one alpha particle as it accelerates from plate A to plate B.2
(b) Determine the speed of the alpha particle as it reaches plate B.3
75 marks
An X-ray machine contains a linear accelerator that accelerates electrons towards a metal target. The electrons are accelerated across the gap from P to Q by a potential difference of 15·0 kV.
(a) Calculate the work done on an electron as it accelerates from P to Q.2
(b) The electron starts from rest at P. Determine its speed as it reaches Q.3
83 marks
Two parallel metal plates are connected to a supply as shown. The electric field between them has not been drawn.
(a) Describe the electric field pattern between the two plates. Your answer should refer to the shape and spacing of the field lines and to their direction.2
(b) An electron is now released from rest next to the negative plate. State the direction in which it moves.1
Push
7 marksTwo or more steps, an unfamiliar context, and a judgement to justify.
95 marks
An ion of mass 3·82 × 10⁻²⁶ kg enters the gap between two charged plates travelling at 5·0 × 10⁵ m s⁻¹, and leaves it travelling at 1·4 × 10⁶ m s⁻¹. The potential difference across the gap is 9·00 kV.
(a) Calculate the kinetic energy gained by the ion as it crosses the gap.3
(b) Determine the charge on the ion.2
102 marks
A pupil says:
"A cyclotron and a linear accelerator are really the same machine — both use an alternating supply to push the particles along."State one important difference between the two machines, and explain why a cyclotron can reach a high speed in a much smaller space than a linear accelerator can.
Your result
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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.