AQA A Level Physics Paper 2 June 2022 question paper 7408/2

Figure 1 shows an electric steam iron.

Water from a reservoir drips onto an electrically-heated metal plate. The water boils and steam escapes through holes in the metal plate.

The electrical power of the heater inside the iron is 2.1 kW.

Assume that all the energy from the heater is transferred to the metal plate.

The metal plate has a mass of 1.2 kg and is initially at a temperature of 20 °C. The heater is switched on. After a time t the metal plate reaches its working temperature of 125 °C.

Calculate t.

specific heat capacity of the metal = 450 J kg⁻¹ K⁻¹

The metal plate is maintained at its working temperature. Water at 20 °C drips continuously onto the metal plate. Steam at 100 °C emerges continuously from the iron.

The maker claims that the iron can generate steam at a rate of 60 g min⁻¹.

Determine whether this claim is true.

specific latent heat of vaporisation of water = 2.3 10⁶ J kg⁻¹ specific heat capacity of water = 4200 J kg⁻¹ K⁻¹

In the kinetic theory model, it is assumed that there are many identical particles moving at random. State two other assumptions made in deriving the equation pV = Nm (c_rms)².

Explain why molecules of a gas exert a force on the walls of a container. Refer to Newton’s laws of motion in your answer.

A sealed flask of volume 0.35 m³ contains an ideal gas at a pressure of 220 kPa. The mean kinetic energy of the gas molecules is 6.7 10⁻²¹ J.

Calculate the amount of gas in the container.

Figure 2 shows the variation of pressure with volume for a fixed mass of an ideal gas at constant absolute temperature T.

Draw, on Figure 2, the graph for the same gas at temperature 2 T.

An isolated solid conducting sphere is initially uncharged. Electrons are then transferred to the sphere.

State and explain the location of the excess electrons.

Figure 3 shows how the electric potential V varies with distance r from the centre of the sphere. The radius of the sphere is 0.10 m.

The magnitude of the electric field strength E is related to V by E =.

Determine, using this relationship, the magnitude of the electric field strength at a distance 0.30 m from the centre of the sphere.

State an appropriate SI unit for your answer.

The sphere acts as a capacitor because it stores charge at an electric potential.

Show that the capacitance of the sphere is approximately 1 × 10⁻¹¹ F.

Electrons leak away from the sphere with time and the amount of energy stored by the sphere decreases. At one instant, the magnitude of the electric potential of the sphere has fallen to 1.0 × 10⁶ V.

Calculate, for this instant, the change in the energy stored by the sphere.

The lines in Figure 4 show the shape of the gravitational field around two stars G and H.

Compare, with reference to Figure 4, the masses of G and H.

X and Y are two points in the field.

Annotate Figure 4 to show the field direction at X and the field direction at Y.

A spherical asteroid P has a mass of 2.0 × 10²⁰ kg.

The gravitational field strength at its surface is 0.40 N kg⁻¹.

Calculate the radius R of P.

Sketch, on Figure 5, the variation of the gravitational field strength g with distance r. The distance r is measured from the centre of P.

Explain what is represented by the area under the graph between r = R and r = 2 R on Figure 5.

Asteroid P approaches the two stars G and H. Figure 6 shows one position of P close to H.

The gravitational force on P from G is 6.38 × 10¹² N.

Calculate the magnitude of the acceleration of P.

Explain why P cannot have a circular orbit around H.

Figure 7 shows a transformer.

Explain the functions of the core and the secondary coil.

Figure 8 shows a cross-section through the transformer core. Thin iron sheets are separated by material M.

Explain how the efficiency of the transformer is increased by constructing the core in this way.

Figure 9 shows a schematic diagram of a power transmission system.

Voltages between 33 kV and 400 kV are used for long-distance transmission.

Suggest why engineers have chosen 132 kV for this system.

The industrial consumers use 72 MW of power. Transformers 1 and 2 each have an efficiency of 98% and the transmission line has an efficiency of 94%.

Calculate the current in the 25 kV line from the power station.

Fission and fusion are two processes that can result in the transfer of binding energy from nuclei.

State what is meant by the binding energy of a nucleus.

Calculate, in MeV, the binding energy for a nucleus of iron 5626Fe.

Figure 10 shows a graph of average binding energy per nucleon against nucleon number for common nuclides.

The nuclide labelled X in Figure 10 undergoes fission.

Annotate Figure 10 with F₁ and F₂ to show one possible pair of nuclides resulting from the fission of X.

Figure 11 shows a graph of N against Z for stable nuclides.

Deduce the likely initial mode of decay of F₁ and F₂. Refer to Figure 11 in your answer.

Section B

Each of Questions 07 to 31 is followed by four responses, A, B, C and D.

For each question select the best response.

An ideal gas, initially at 300 K, is compressed to half its original volume. It is then cooled at constant volume until the pressure is restored to its initial value.

What is the final temperature of the gas?

A fixed volume of an ideal gas is heated.

Which row gives quantities that double when the kelvin temperature of the gas doubles?

A planet of radius R and mass M has a gravitational field strength of g at its surface.

Which row describes a planet with a gravitational field strength of 4 g at its surface?

The Moon orbits the Earth in 27 days.

What is the angular speed of the Moon’s orbit?

The radius of the Earth is R and the acceleration due to gravity at the surface of the Earth is g.

What is the escape velocity for a mass m at the surface of the Earth?

A planet has a mass M and a radius R. Loose material at the equator only just remains in contact with the surface of the planet. This is because the speed at which the planet rotates is very large.

What is the period of rotation of the planet?

Satellites N and F have the same mass and move in circular orbits about the same planet. The orbital radius of N is less than that of F.

Which is smaller for N than for F ?

When an electron moves at a speed v perpendicular to a uniform magnetic field of flux density B, the radius of its path is R. A second electron moves at a speed perpendicular to a uniform magnetic field of flux density 4 B.

What is the radius of the path of the second electron?

A particle of mass m and charge Q is accelerated from rest through a potential difference V. The final velocity of the particle is u. A second particle of mass and charge 2Q is accelerated from rest through a potential difference 2 V.

What is the final velocity of the second particle?

The diagram shows a uniform electric field of strength 15 V m. The length RS is perpendicular to the field and the line ST is parallel to the field.

What is the total change in electrical potential energy for a charge of 3.0 μC moving from R to T ?

A switch S allows capacitor C to be completely charged by a cell and then completely discharged through an ammeter. The emf of the cell is 4.0 V and it has negligible internal resistance. The capacitance of C is 0.40 F and there are 8000 charge−discharge cycles every

What are the magnitude and direction of the average conventional current in the ammeter?

A 30 μF capacitor is charged by connecting it to a battery of emf 4.0 V. The initial charge on the capacitor is Q₀.

The capacitor is then discharged through a 500 kΩ resistor. The time constant for the circuit is Τ.

Which is correct?

Capacitor X of capacitance C has square plates of side length l and separation d and is

Capacitor Y has square plates of side length 3l and separation and is made with a

What is the capacitance of Y ?

A parallel plate capacitor is connected across a battery and the energy stored in the capacitor is E. Without disconnecting the battery, the separation of the plates is halved.

What is the energy now stored in the capacitor?

A fully charged capacitor of capacitance 2.0 mF discharges through a 15 kΩ resistor.

What fraction of the stored energy remains after 1.0 minute?

A horizontal wire of length 0.25 m carrying a current of 3.0 A is perpendicular to a magnetic field. The mass of the wire is 3.0 × 10⁻³ kg and the weight of the wire is supported in equilibrium by the magnetic field.

What is the flux density of the magnetic field?

A coil is rotated at frequency f in a uniform magnetic field. The magnetic flux linking the coil is a maximum at time t₁ and the emf induced in the coil is

What is the smallest value of t₁ − t₂?

Power P is dissipated in a resistor of resistance R carrying a direct current I.

A second resistor of resistance 2 R carries an alternating current with peak value I.

What is the power dissipated in the second resistor?

What was deduced or observed in the Rutherford scattering experiment?

Which row is correct for α, β and γ radiation?

A sample of radioactive material consists of 200 g of nuclide P and 100 g of nuclide Q.

Nuclide P has a half-life of 2 days and nuclide Q has a half-life of 4 days.

What is the total mass of nuclides P and Q after 12 days?

A nuclide has a half-life of 10 ms.

The decay constant for this nuclide lies between

Which provides evidence for the existence of energy levels in nuclei?

Which is not true for gamma radiation?

235 In a thermal reactor, induced fission occurs when a 92 U nucleus captures a neutron. Which statement is true?