AQA GCE AS Level Physics AS Paper 1 June 2022 question paper 7407/1

A sigma-plus (Σ⁺) particle and an unidentified particle Y are produced by the strong interaction between a positive pion (π⁺) and a proton (p).

This interaction is represented by the equation:

Complete Table 1 to show the baryon number B, charge Q and strangeness S for the particles in this interaction.

Which particle in Table 1 has the quark structure uus ?

Tick () one box.

Deduce which particle, π⁺ or Y, has the greater charge-to-mass ratio. Justify your conclusion.

A sample of bromine gas contains a mixture of two isotopes. An experiment is done to find the percentage of each isotope in this sample.

In the experiment, the gas is ionised by a beam of electrons.

Explain how the beam of electrons causes a particle of the gas to have a charge of +1 e.

The gas consists of bromine molecules. Each molecule has two bromine atoms. The experiment finds that the bromine molecules contain 158, 160 or 162 nucleons.

Figure 1 shows the percentage of these different molecules in the sample.

Bromine has a proton number of 35 The two isotopes in the sample have different nucleon numbers.

Calculate the number of neutrons for the isotope that has the greater nucleon number.

Deduce the percentage of each isotope in the gas. Justify your conclusion.

A satellite system is used to measure the height h of the top of an ice sheet above the surface of the ocean. The satellite emits two pulses A and B of infrared radiation. A is incident on the surface of the ocean and B is incident on the top of the ice sheet as shown in Figure 2.

The frequency of the infrared radiation is 3.8 × 10¹⁴ Hz. Each pulse has a duration of 6.0 ns.

Calculate the number of cycles in each pulse.

A and B reflect and return to the satellite. The travel time is the time between the emission of a pulse and its return to the satellite.

The difference in the travel times of A and B is 10.7 μs.

Calculate h.

Some of the infrared radiation enters the ice sheet.

Figure 3 shows the path of infrared radiation that refracts at a sloping part of the ice sheet.

Calculate the refractive index of the ice.

Calculate the wavelength of the infrared radiation when it is inside the ice sheet.

An isolated metal plate is given a negative charge. Electromagnetic radiation is incident on the plate. The plate loses its charge due to the photoelectric effect.

Discuss how the rate of loss of charge from the plate depends on the frequency and intensity of the incident radiation.

In your answer you should explain why:

the plate loses its charge

the photoelectric effect occurs only for frequencies greater than a particular value

the rate of loss of charge increases with intensity for radiation above that particular value of frequency.

Charged particles are emitted from the metal plate with a maximum kinetic energy of 1.1 eV when radiation of frequency 1.2 × 10¹⁵ Hz is incident on the plate.

Calculate, in eV, the work function of the metal.

Figure 4 shows apparatus used to demonstrate the wave – particle duality of electrons.

The heated filament emits slow-moving electrons.

In region P, the electrons are accelerated to a high speed. At Q, the fast-moving electrons are incident on the graphite target. R is a point on one of the bright rings that are formed where the electrons strike the fluorescent screen.

The electrons demonstrate wave-like and particle-like behaviour as they travel from the filament to the screen.

State and explain at which of P, Q or R the electrons are demonstrating wave-like behaviour.

The apparatus is adjusted so that the electrons are incident on the graphite target with a greater speed.

Explain why the bright rings formed on the screen now have a smaller diameter.

Figure 5 shows a worker of weight 750 N on a uniform platform. The weight of the worker is acting at a horizontal distance d from end A.

Throughout this question, assume that the platform is horizontal and that all cables obey Hooke’s law.

The platform weighs 1800 N and is suspended by vertical cables P and Q. Each cable has an unstretched length of 3.0 m. The horizontal distance between P and Q is 3.6 m.

The worker moves to a position where the tension in the left-hand cable P is 1150 N.

Calculate d for this position.

Figure 6 shows how the extension of P varies with d as the worker walks slowly along the platform from A to B.

The worker moves to a position X where the strain in P is 6.0 × 10⁻⁵.

Determine d for position X.

The cable material has a Young modulus of 1.9 × 10¹¹ N m⁻².

Calculate the tensile stress in P when the worker is at X.

The original cables P and Q are replaced.

Table 2 shows how the properties of the original cables compare with the replacement cables.

After the cables have been replaced, the worker walks slowly from A to B.

Draw on Figure 7 a line to show the variation of the extension of the replacement left-hand cable with d. The original line from Figure 6 is shown on Figure 7 as a dashed line to help you.

Figure 8 shows a cyclist going up a hill.

The angle θ of the slope of the hill is constant. The total mass m of the cyclist and bicycle is 65 kg.

Write an expression for the component of the total weight parallel to the slope.

The useful power output of the cyclist is 310 W. The cyclist has a steady speed of 1.63 m s⁻¹.

Assume that air resistance is negligible at this speed.

Calculate θ.

Figure 9 shows an alternative ‘zig-zag’ path taken by the cyclist up the same hill. She maintains a steady speed of 1.63 m s⁻¹.

Discuss how her useful power output when taking the path in Figure 9 compares with her useful power output in Question 07.2.

The cyclist reaches the top of the hill. She then travels back down the hill in a straight line. The bicycle rolls freely without the cyclist pushing the pedals or applying the brakes.

Figure 10 shows the variation of her velocity with time as she goes down the hill.

Determine the acceleration of the cyclist 10.0 s after she begins to go down the hill.

Energy transfers occur as the cyclist travels down the hill.

Outline how these energy transfers explain the shape of the graph in Figure 10.

Figure 11 shows a variable resistor that has a maximum resistance of 25 Ω. A sliding contact P is mounted on a thick copper bar. P can be set to any position between X and Y.

Figure 12 shows the variable resistor being used to investigate the variation of current with voltage for a filament lamp. The normal operating voltage of the lamp is 12 V.

The 12 V battery has negligible internal resistance.

The position of P is adjusted so that the reading on the voltmeter is at its minimum value of 0.75 V.

Calculate the resistance of the lamp when the voltmeter reading is 0.75 V.

Figure 13 shows the variation of current with voltage for the lamp between 2 V and 12 V.

Calculate the resistance of the lamp when the voltage across the lamp is 8.0 V.

Explain, in terms of electron movement, why the resistance of the filament lamp changes as the voltage changes as shown in Figure 13.

Figure 14 shows an alternative circuit used to investigate the variation of current with voltage for the lamp.

The circuit components are the same as in Figure 12. When the voltage across the lamp is 12 V its resistance is 6.0 Ω.

P is moved to position Y.

Calculate the total resistance of the circuit.

Calculate the power transferred by the battery when P is at position Y.

A student wants to control the brightness of the lamp.

He gives two reasons why the circuit in Figure 14 is better than the circuit in Figure 12 for controlling the brightness. The two reasons are:

• the Figure 14 circuit can achieve a greater range of voltages across the lamp

• the Figure 14 circuit is more efficient at transferring energy to the lamp.

Discuss, without calculation, whether either of these two reasons is correct.