OCR A Level Physics A Unified Physics June 2022 question paper H556/03

The table shows some data on the planet Venus.

Calculate the magnitude of the gravitational field strength g at the surface of Venus.

Give your answer to 3 significant figures.

=........ N kg^–1 g

Two identical space probes, A and B, land on a flat surface on Venus.

Probe A lands at the north pole. Probe B lands on the equator.

Each probe has mass 760 kg and volume 1.7 m³.

Calculate the centripetal acceleration a of probe B at the equator due to the rotation of Venus about its axis.

=........ m s^–2 a

The atmosphere exerts the same upthrust on each probe.

Using your answer to (a), calculate the upthrust acting on each probe.

Explain which probe will experience the greater normal contact force from the surface of Venus.

A student investigates the oscillations of a uniform rod of length L which is pivoted at the top, as shown in Fig. 2.1.

Describe how to determine accurately the period T of oscillations of this rod.

The relationship between the frequency f of the oscillations of the rod and its length L is

where g is the acceleration of free fall.

The student varies the length L of the rod and determines the period T for each length.

The student plots a graph of T² against L, shown in Fig. 2.2. A line of best fit has already been drawn.

Show that the gradient of the graph is given by the equation

Draw a line of worst fit on Fig. 2.2.

Use your line of worst fit to calculate the percentage uncertainty in g.

In beta-plus decay, a proton decays into three other particles.

Write a nuclear equation for this process.

Describe the origin of the microwave background radiation.

The figure below shows how the intensity of the microwave background radiation varies with its wavelength .

The peak intensity is at a wavelength of 1.1 mm.

This spectrum of microwave background radiation changes with temperature according to Wien’s displacement law.

Suggest and explain how the spectrum might have looked in the distant past. You may draw on the figure to support your answer.

Calculate the energy of a photon which has a wavelength of 1.1 mm.

Estimate the number of photons of microwave background radiation incident per second on the back of your hand.

Assume that all emitted photons have the energy calculated in (ii), and that the back of your hand has a surface area of 150 cm².

number of photons per second =........ s^–1

A student experiments with microwaves emitted from a transmitter. The frequency f of the microwaves from the transmitter can be adjusted.

The microwaves are produced by an alternating current in the transmitter.

In one experiment, f is 11 GHz. In a wire in the transmitter, the magnitude of the maximum alternating current is 20 mA. The wire has cross-sectional area 1.4 × 10^–8 m² and is made of a metal with free electron number density 8.0 × 10²⁸ m^–3.

The student models the average motion of the free electrons in the wire as simple harmonic motion.

Use your answer to (i) to calculate the amplitude A of this motion.

Without further calculation, explain how the maximum acceleration of a free electron varies as the frequency f is adjusted, provided that the maximum alternating current remains constant.

The student connects two microwave transmitters X and Y, and places them in front of a microwave detector D, as shown in the diagram below.

The transmitters X and Y produce coherent vertically polarised microwaves with the same frequency f.

The detector D is sensitive to vertically polarised microwaves only.

When the detector D is moved along the line PQ, a pattern of maximum and minimum intensity is observed. Adjacent maxima are separated by a distance x.

* Explain:

• why this pattern of intensity occurs

• the expected relationship between the frequency f and the distance x

• how to verify this relationship experimentally.

Define the time constant of a circuit containing a capacitor of capacitance C and a resistor of resistance R.

By drawing a suitable tangent to the graph in Fig. 6.3, calculate the maximum current in the resistor.