AQA GCE AS Level Physics AS Paper 1 June 2019 question paper 7407/1

Deuterium is an isotope of hydrogen. Its nucleus contains one proton and one neutron.

Calculate the specific charge of the deuterium nucleus.

The proton and neutron in the deuterium nucleus are held together by the strong nuclear force.

Which is an exchange particle of the strong nuclear force? Tick (✓) one box.

The deuterium nucleus is stable.

Describe how the variation of the strong nuclear force with distance contributes to the stability of the deuterium nucleus.

Tritium is an isotope of hydrogen. Its nucleus contains one proton and two neutrons. Tritium undergoes radioactive decay.

Three modes of radioactive decay are

• alpha decay

• beta minus (β⁻) decay

• electron capture.

Deduce which of these modes could produce the nucleus of another element when the tritium nucleus decays.

A battery of emf 7.4 V and negligible internal resistance is used to power a heating element inside a glove. The heating element has a resistance of 3.7 Ω.

The designers state that the battery can produce a current of 2.0 A in the heating element for 240 minutes.

Calculate the energy dissipated in the heating element in this time.

The length of the heating element needed is about 0.85 m. The designer considers using a carbon fibre tape for the heating element. Table 1 gives information for the carbon fibre tape.

Deduce whether the carbon fibre tape is suitable for making the heating element for the glove.

A light emitting diode (LED) is used to indicate that the switch in the glove is closed, as shown in Figure 1. Resistor R limits the current in the LED.

Figure 2 shows part of the characteristic graph for the LED.

The circuit is designed so that the potential difference across the LED is 2.2 V when the switch is closed.

Calculate the resistance of R.

Figure 3 shows a fairground ride called a ‘reverse bungee’.

Two identical stretched elastic ropes are fixed to a cage with passengers inside. The loaded cage is held in place by a clamp. When the clamp is released the elastic ropes accelerate the loaded cage vertically into the air.

P is the point where the rope attaches to the top of the vertical tower. Q is the point where the rope attaches to the cage. Q is level with the centre of mass of the loaded cage.

Before release, the tension T in each elastic rope is 3.7 × 10⁴ N and each rope makes an angle of 20° with the vertical tower.

The total mass M of the loaded cage is 1.2 × 10³ kg and the mass of the elastic ropes is negligible.

Show that the downward force F exerted by the clamp on the loaded cage is about

Calculate the initial acceleration of the loaded cage when the clamp is released.

The unstretched length of each elastic rope is 24 m. The ropes obey Hooke’s Law for all extensions used in the ride. The vertical distance between points P and Q on Figure 3 is 35 m.

Show that the total elastic potential energy stored in both ropes before the loaded cage is released is about 5 × 10⁵ J.

The designers of the ride claim that the loaded cage will reach a height of 50 m above Q.

Deduce whether this claim is justified.

The designers also claim that the loaded cage reaches a maximum speed of at least

Calculate, in J, the kinetic energy of the loaded cage when it travels at 90 km h⁻¹.

Deduce without further calculation whether the maximum speed claim is justified.

In 1870 John Tyndall sent a beam of light along a stream of water. Figure 4 shows a modern version of Tyndall’s experiment using a laser beam. Water has a refractive index of 1.33

Explain why the laser beam stays inside the stream of water.

Calculate the speed of the laser light in the water. Give your answer to an appropriate number of significant figures.

Calculate the critical angle for the waterair boundary.

Tyndall’s experiment led to the development of optical fibres. Figure 5 shows a step-index optical fibre.

Discuss the properties of a step-index optical fibre.

Your answer should include:

• the names of part X and part Y

• a description of the functions of X and Y

• a discussion of the problems caused by material dispersion and modal dispersion and how these problems can be overcome.

Scientists use optical fibres to monitor earthquakes. Light travelling through an optical fibre can be reflected by impurities in the fibre, as shown in Figure 6.

Earthquakes bend the optical fibre slightly, as shown in Figure 7. This changes the amount of reflected light.

Suggest why the amount of reflected light changes as the fibre bends. You may draw on Figure 7 as part of your answer.

The waves caused by earthquakes can be longitudinal or transverse.

Describe the difference between longitudinal waves and transverse waves.

A student investigates moments by suspending a 100 cm ruler from two force meters, A and B. A and B are attached to the ruler 12.0 cm from each end. Their supports are adjusted to make A and B vertical and the ruler horizontal.

Figure 8 is a simplified diagram of the experiment.

The ruler is uniform and weighs 1.12 N.

Determine the reading on A.

The student suggests that the forces exerted on the ruler by A and B act as a couple.

Discuss whether his suggestion is correct.

A second student sets up the same apparatus as shown in Figure 9. She suspends the mass in the same position on the ruler as in question 05.3. She moves the supports to make A and B vertical but does not make the ruler horizontal.

Discuss whether the readings on A and B taken by this student are different to those in question 05.3.

Scientists at CERN have produced atoms of antihydrogen. An atom of antihydrogen contains the antiparticle of the proton and the antiparticle of the electron.

State what is meant by an antiparticle.

Complete Table 2 with the names of the antiparticles in an atom of antihydrogen.

The particles in antihydrogen can be made by pair production.

Calculate the total minimum energy, in J, needed to produce the particles in one atom of antihydrogen.

Line emission spectra of hydrogen and antihydrogen have been compared.

Explain in terms of energy changes how line emission spectra are produced.