4PH1/2PR — January 2023 (Edexcel IGCSE Physics): Past Paper

The diagram is an incomplete Hertzsprung‑Russell diagram which astronomers use to compare stars. R Q P Colour

The y‑axis label is missing. Which of these is the correct label for the y‑axis?

The box contains words to identify the shaded areas P, Q and R on the Hertzsprung‑Russell diagram. white dwarfs main sequence red giants black holes supernovae dwarf planets Use words from the box to identify P, Q and R. P Q R

Explain which side of the diagram contains stars with the highest surface temperature.

This is a question about electromagnetic waves.

State which colour in the visible spectrum has the shortest wavelength.

Explain a hazard of ultraviolet radiation to the human body.

State the formula linking speed, wavelength and frequency of a wave.

Calculate the frequency of radio waves with a wavelength of 15 m. [speed of light = 300 000 000 m/s] frequency = Hz

A tumble dryer is a household device that dries clothes. The clothes rotate in a heated cylinder. Clothes often stick together when they are dry because they become electrostatically charged. A student investigates how different materials charge electrostatically in a model tumble dryer. The diagram shows the model tumble dryer. direction of rotation cylinder squares of material This is the student’s method.

• put four dry squares of the same material into the cylinder
• rotate the cylinder at constant speed for three minutes
• remove any squares that are stuck together
• measure the force needed to pull the squares apart
• repeat this for squares of different material

Name a device the student could use to measure a force.

State the independent and dependent variables in this investigation. independent dependent

State a control variable in this investigation.

Explain how the squares of material stick together. Use ideas about electrostatic charge in your answer.

The table shows some of the student’s results. Mean force to separate squares Material in N wool 5.4 polyester 3.2 acrylic 6.5 Explain which type of graph is the most appropriate to present the results from this investigation.

No printed figure accompanies this part — in the paper you would draw the diagram (or label the apparatus) in the answer space provided.

State the formula linking charge, current and time.

When the squares of material are pulled apart there is a small spark. There is a current of 4.3 × 10⁻⁶ A in the air for a time of 2.3 × 10⁻³ s. Calculate the charge that is transferred. charge = C

Diagram 1 shows a circuit built by a student. 83 mA 17 Ω 6.2 Ω 228 mA Diagram 1

State the formula linking voltage, current and resistance.

Calculate the voltage across the 17 Ω resistor. voltage = V

State the voltage across the 6.2 Ω resistor. voltage = V

Calculate the current in the battery. current = mA

Diagram 2 shows a second circuit built by the student using the same battery and resistors. 17 Ω 6.2 Ω Diagram 2 Explain how the current in the battery will change now the resistors are connected in series. You do not need to do any calculations in your answer.

A transformer is used to charge a mobile phone. The diagram shows a label on the transformer. input voltage: 230 V input current: 0.067 A output voltage: 5.0 V output current: 3.1 A

Explain how the information in the label shows that the transformer is a step‑down transformer.

Show that the transformer is approximately 100% efficient.

State the formula linking input voltage, output voltage and turns ratio for a transformer.

The primary coil has 1500 turns. Calculate the number of turns on the secondary coil. turns on secondary coil =

This question is about the use of water in central heating systems.

A student does an investigation to find the specific heat capacity of water. This is the list of equipment they use. • heater with a power output of 50 W • power supply • beaker • water • thermometer • stopwatch • connecting leads • balance Describe an investigation the student could use to find the specific heat capacity of water. You may draw a diagram to help your answer.

The diagram shows a simplified central heating system viewed from above. radiator boiler house radiator pipe radiator Pipes transport hot water around a house to radiators and back to the boiler. The boiler heats water from 16 °C to 65 °C.

Calculate the energy transferred from the boiler to 75 kg of water to raise the temperature of the water from 16 °C to 65 °C. [for water, specific heat capacity = 4200 J/kg °C] energy = J

The radiators transfer energy from the water to the air in the house. The temperature of the water in the heating system decreases by 4 °C due to heat transferred to the air. This causes the air in the house to increase in temperature by 15 °C. The mass of air in the house and the mass of water in the heating system are approximately the same. Explain why there is a larger temperature change in the air.

A crumple zone is a safety feature in a car. It is a part of the car that is designed to collapse during a collision. A student investigates the effectiveness of crumple zones. The student rolls two model cars down a ramp. Each car comes to rest when it hits a large metal block. A data logger measures the mean force applied to the car during the collision with the block. The diagram shows the equipment used in the investigation. data logger metal ramp block 0.0 N Car 1 has a paper crumple zone at the front. Car 2 has no paper crumple zone. The table shows the student’s results. Mean force on car from block Velocity just before car hits block Car in N in m/s 1 2.5 3.0 2 4.9 3.0

The mass of each car is 0.074 kg. Calculate the time taken for the velocity of car 1 to decrease from 3.0 m/s to 0.0 m/s. time taken = s

State the magnitude and direction of the force on the metal block, when car 2 collides with the block. magnitude = N direction =

Explain why the mean force from the block on car 1 is smaller than the mean force on car 2.

Between 1929 and 1931, physicists Hubble and Humason investigated the red‑shift of light from galaxies at different distances from the Earth. The distance unit they used is the megaparsec (Mpc).

Describe what is meant by the term red‑shift.

The graph shows some of the results of their investigation. 0.10 0.08 0.06 Change in wavelength in nm 0.04 0.02 0.00 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Distance in Mpc

Draw a circle to show the anomalous data point.

Draw the line of best fit on the graph.

The reference wavelength of the light used in this investigation is 660 nm. Use information from the graph to determine the velocity of a galaxy at a distance of 0.75 Mpc. [speed of light = 300 000 km/s] velocity = km/s

Explain why the graph from Hubble’s investigation provides evidence for the expansion of the universe.