AQA GCE AS Level Physics AS Paper 1 June 2025 question paper 7407/1

Hydrogen has three naturally occurring isotopes. One of these isotopes is

Calculate the specific charge of a nucleus of hydrogen-3.

The specific charge of the hydrogen-3 nucleus is less than the specific charges of the nuclei of the other two isotopes.

Suggest why.

Kaons (K) and pions (π) are produced when a beam of antiprotons is incident on a sample of hydrogen gas.

One reaction that occurs is

Deduce, with reference to appropriate conservation laws, the quark structure of the K⁰ produced in this reaction.

One possible decay of a π + particle is

where A is a charged lepton.

Suggest, with reference to appropriate conservation laws, the name of A and the name of B.

An optical fibre consists of a glass core surrounded by cladding.

Monochromatic light enters the glass core of the optical fibre from air.

What happens to the frequency of the light as it enters the glass core?

Tick (✓) one box.

The refractive index of the glass core is 1.51

The critical angle at the core–cladding boundary is 80.7°

Calculate the refractive index of the cladding.

Figure 1 shows a ray of light that is incident on the centre of the core. At the air–core boundary, the angle of incidence of this ray is θ_A and the angle of

When θ_B is greater than 9.3°, the ray will not be transmitted through the optical fibre.

Calculate the maximum value of θ_A for the ray to be transmitted through the optical fibre.

A fluorescent tube contains a low-pressure gas consisting of mercury atoms.

Figure 3 shows the four lowest energy levels of a mercury atom.

A mercury atom inside the fluorescent tube is in its ground state n = 1

An electron is travelling inside the tube. The electron has a kinetic energy of 13.10 × 10⁻¹⁹ J when it collides with the mercury atom.

As a result of the collision, the mercury atom is excited to its n = 3 energy level. Immediately after the collision, the electron is moving with a speed that is smaller than before the collision. Assume that the kinetic energy of the mercury atom does not change.

Calculate the de Broglie wavelength of this electron immediately after the collision.

The excited mercury atoms inside the fluorescent tube can emit photons of ultraviolet light, each of energy 7.83 × 10⁻¹⁹ J.

Calculate, in nm, the wavelength of a photon with this energy.

The fluorescent tube has an input power of 18 W.

82% of the input power is converted into ultraviolet photons, each of

Calculate the number of these photons emitted in one second.

Explain how the coating of the fluorescent tube emits white light.

In your answer you should:

• describe the processes that take place in the coating

• suggest why there are many more visible photons than ultraviolet photons emitted by the tube.

State the principle of moments.

Figure 4 shows a trolley at rest on a horizontal surface. A load is fixed to the base of the trolley.

Assume that the forces in Figure 4 are coplanar.

The distance between the centre of the front wheels and the centre of the back wheels is 85 cm.

The total reaction force at the front wheels is 97 N and the total reaction force at the back wheels is R.

The trolley and load have a total weight W.

The perpendicular distance between the lines of action of the forces W and R is 12 cm.

Calculate R.

Figure 5 shows the trolley after its back wheels have been lifted onto a step. The trolley is stationary.

When the back wheels are on the step, the moment of W about the centre of the back wheels is less than that in Figure 4.

Explain why.

Deduce how the magnitude of R₁ in Figure 5 compares with the value of 97 N in Figure 4.

Figure 6 shows a stationary lift suspended using three steel cables P, Q and R. The centre of mass of the lift is vertically below cable P.

The mass of the lift is 850 kg. The angle between Q and R is 75° Q and R each have an unstretched length of 2.0 m. The cross-sectional area of each cable is 1.4 × 10⁻⁴ m². The Young modulus of the steel is 2.1 × 10¹¹ Pa.

Determine the extension of Q.

Figure 7 is a velocity–time graph for the lift as it travels upwards from ground level.

Determine the gravitational potential energy gained by the lift during the first 1.5 s of the motion.

Q and R are connected to P as shown in Figure 6.

Determine the tension in P during the last 2.0 s of the motion.

After 4.0 s of the motion, the lift is moving at a constant velocity and has travelled 5.5 m from ground level. An object becomes detached from the underside of the lift.

Determine the velocity of the object when it reaches ground level.

Sketch on Figure 8 the variation with time of the kinetic energy of the object from when it becomes detached until it hits the ground. No calculations are required.

Figure 9 shows the variation of potential difference V with current I for a thermistor T

Discuss, for the range 0 to 9 mA, the characteristic of T shown by Figure 9.

In your answer you should:

describe how to produce a characteristic experimentally

describe, in terms of resistance, the behaviour of T

explain, with reference to temperature, the behaviour of T.

Figure 10 shows thermistor T in series with a fixed resistor R and a battery.

The variation of V with I shown in Figure 9 applies to T in this circuit.

The battery has an emf of 10.0 V and negligible internal resistance.

The current in T is 1.0 mA.

Determine the resistance of R.

State what is meant by the threshold frequency of radiation in the photoelectric effect.

When magnesium is illuminated with monochromatic electromagnetic radiation, photoelectrons are emitted. For this radiation, the maximum kinetic energy of the photoelectrons is 5.47 × 10⁻¹⁹ J and the stopping potential is V_s.

Calculate V_s.

The radiation incident on the magnesium has a frequency of 1710 THz.

Calculate the work function of the magnesium.

The frequency f of the electromagnetic radiation is varied.

Figure 11 shows the variation of E_k(max) with f for magnesium.

Metal X and metal Y are illuminated by radiation with the same range of frequencies as used for the magnesium.

Sketch, on Figure 11, graphs to show how E_k(max) varies with f for X and for Y. Label your graphs X and Y. Go on to explain your reasoning.

work function of X > work function of magnesium > work function of Y