Question 1

1.5 mJ of work is done when a charge of 30 µC is moved between two points, M and N, in an electric field.

What is the potential difference between M and N?

  A  

20 mV

  B  

20 V

  C  

45 V

  D  

50 V

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Question 2

The ionisation potential for the atoms of a gas is V. Electrons of mass m and charge e travelling at a speed v can just cause ionisation of atoms in the gas.

What is v?

2 me V​
m2 e V​
√2 me V​​
√m2 e V​​

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Question 3

A positive charge of 2.0 × 10−4 C is placed in an electric field at a point where the potential is +500 V.

What is the potential energy of the system?

  A  

1.0 × 10−1 J

  B  

1.0 × 10−1 J C−1

  C  

4.0 × 10−7 J

  D  

4.0 × 10−7 J C−1

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Question 4

An ion is accelerated by a series of electrodes in a vacuum. A graph of the power supplied to the ion is plotted against time.

What is represented by the area under the graph between two times?

  A  

the change in kinetic energy of the ion


  B  

the average force on the ion


  C  

the change in momentum of the ion

  D  

the change in velocity of the ion

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Question 5

Two protons are separated by distance r.

The electrostatic force between the two protons is X times the gravitational force between them.

What is the best estimate for X?

  A  

1020

  B  

1028

  C  

1036

  D  

1042

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Question 6

The diagram shows the path of a proton being deflected by the nucleus of an atom.

Point P is the position of the proton when it is closest to the nucleus.

What is not true about the proton along its path at P?

  A  

its rate of change of momentum is at a minimum

  B  

its kinetic energy is at a minimum

  C  

its potential energy is at a maximum


  D  

its acceleration is at a maximum

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Question 7

A particle of mass m and charge q is accelerated through a potential difference V over a distance d.

What is the average acceleration of the particle?

m dq V​
q dm V​
m q dV​
m qd V​

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Question 8

An electron moves through a distance of 0.10 m parallel to the field lines of a uniform electric field of strength                2.0 kN C−1.

What is the work done on the electron?

  A  

zero

  B  

1.6 × 10−17 J


  C  

3.2 × 10−17 J


  D  

1.6 × 10−21 J


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Question 9

The electric potential at a distance r from a positive point charge is 45 V. The potential increases to 50 V when the distance from the point charge decreases by 1.5 m. What is the value of r?

  A  

1.3 m


  B  

1.5 m


  C  

7.9 m


  D  

15 m

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Question 10

A small object of mass m has a charge Q. The object remains stationary in an evacuated space between two horizontal plates. The plates are separated by a distance d and the potential difference between the plates is V.

What is V?

dm Q g​
Qm d g​
dm Q​
Qm d​

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