Synoptic Exam Questions (Paper 1 & 2) (AQA A Level Physics): Exam Questions

The core of a thermal nuclear reactor contains a number of components that are exposed to moving neutrons. 

State what happens to a neutron that is incident on: 

• the moderator

• a control rod.

A slow-moving neutron collides with a nucleus of an atom of the fuel which induces nuclear fission. 

Describe what happens in the process of induced fission.

A student sets up the arrangement, shown in Figure 8, to demonstrate the principle of moderation in a nuclear reactor.

Figure 8

A golf ball of mass is initially hanging vertically and just touching a hockey ball of mass . The golf ball is pulled up to the side and released. After the collision, the balls move in opposite directions with equal speeds.

Explain, with numerical detail, how this arrangement demonstrates the moderation process in a reactor.

A thermal nuclear reactor produces radioactive waste.

State the main source of the most dangerous waste and describe one problem faced in dealing with the waste.

Thin films of carbon are sometimes used in electronic systems. 

Typical dimensions of such a film are shown in Figure 7.

Figure 7

Calculate the current which passes through the carbon film shown in Figure 7 for an applied voltage of 2.5 mV. 

The resistivity of carbon = 4.0 × 10^–5 Ω m

The applied voltage is kept constant, but the current is now directed through the carbon film as shown in Figure 8.

Figure 8

Show that the current is approximately 6 magnitudes larger when directed through the carbon film, as shown in Figure 8.

A tensile force is applied to the carbon film in Figure 8 in a plane that is normal to the current. 

Without performing any calculations, state and explain how the resistance of the carbon film changes as a result of the applied tensile force, stating one assumption you make.

The International Space Station (ISS) orbits travels around the Earth once every 93 minutes. 

Calculate the angular speed of the ISS.

Calculate the distance of the ISS above the Earth’s surface.

The Soyuz is a Russian spacecraft that carries astronauts to and from the international space station (ISS). The ISS has a mass of approximately 4.2 × 10⁵ kg. 

Calculate the change in kinetic energy of a Soyuz travelling from the Earth’s surface to the ISS.

Without performing any further calculations, explain how the change in kinetic energy relates to the change of the potential energy when the Soyuz travels from the Earth’s surface to the ISS. 

Cyclotrons are used to accelerate particles, such as protons, for a number of applications. 

A cyclotron has two D-shaped regions called ‘dees’ where the magnetic flux density is constant. The dees are separated by a small gap. An alternating electric field between the dees accelerates charged particles. The magnetic field causes the charged particles to follow a circular path. 

Figure 5 shows the path followed by a proton that starts from O.

 Figure 5

State the direction the magnetic field acts over the dees in Figure 5.

Explain why it is not possible for the magnetic field to alter the speed of a proton while it is in one of the dees.

Show that the time taken by a proton to travel around one semi-circular path is independent of the radius of the path.

The maximum radius of the path followed by the proton is 0.46 m and the magnetic flux density of the uniform field is 0.88 T. 

Calculate the maximum speed of a proton when it leaves the cyclotron. 

Ignore any relativistic effects.

The protons leave the cyclotron when the radius of their path is equal to the outer radius of the dees. 

Determine the radius required for the cyclotron to produce protons with a maximum kinetic energy of 25 MeV. 

Ignore any relativistic effects.