Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Electromagnetism
68 practice questions
Topics covered
Practice questions
11–20 of 35 · Normal
Question 11
1 mark · Normal
Answer and check →Which of the following will NOT increase the size of the voltage induced in a wire by electromagnetic induction?
- A.Using a stronger magnet
- B.Moving the wire faster across the magnetic field
- C.Increasing the number of turns in the coil
- D.Using a weaker magnet
Question 12
3 marks · Normal
Answer and see the solution →A student investigates how the induced voltage in a coil changes with the speed of a moving magnet. Her results are shown in the table.
Induced voltage vs. speed of magnet Speed of magnet (cm/s) Induced voltage (V) 2 0.6 4 1.2 6 1.8 8 2.4 (a)[1 mark]Describe the relationship between speed and induced voltage shown by the data.
(b)[2 marks]Predict the induced voltage if the speed of the magnet is increased to 10 cm/s.
Question 13
3 marks · Normal
Answer and see the solution →When a magnet is pushed into a coil of wire, a voltage is produced across the ends of the coil. The voltage disappears if the magnet stops moving.
(a)[2 marks]Explain why a voltage is only induced when the magnet is moving.
(b)[1 mark]Give one way to increase the maximum voltage produced in this experiment.
Question 14
4 marks · Normal
Answer and see the solution →A portable generator is used at a roadworks site to provide electrical power. The generator has a coil rotating inside a strong magnetic field.
Describe how electricity is produced in this generator and state two factors that will increase the amount of electricity generated.
(a)[2 marks]Describe what happens as the generator coil turns inside the magnetic field.
(b)[2 marks]State two ways the amount of electricity generated can be increased.
Question 15
3 marks · Normal
Answer and see the solution →You are given a coil of wire, a bar magnet, and a sensitive voltmeter.
Describe a practical experiment to show electromagnetic induction and how you would demonstrate that the induced voltage depends on the speed of movement.
(a)[1 mark]Describe how you would set up the apparatus to show an induced voltage.
(b)[2 marks]Describe what you would do to investigate how the induced voltage changes with speed.
Question 16
2 marks · Normal
Answer and see the solution →State the purpose of a soft iron core in a transformer.
Question 17
3 marks · Normal
Answer and see the solution →A transformer is used to produce an output voltage of 48 V from a 240 V a.c. mains supply. The primary coil has 960 turns.
Calculate the number of turns needed on the secondary coil to achieve this output voltage.
Question 18
3 marks · Normal
Answer and see the solution →Explain why transformers cannot be used with a direct current (d.c.) supply.
Question 19
4 marks · Normal
Answer and see the solution →The diagram shows a transformer. The secondary coil has 300 turns and produces a voltage of 15 V.
(a)[3 marks]The primary coil has 1200 turns. Calculate the input voltage.
(b)[1 mark]State whether this transformer is step-up or step-down. Give a reason for your answer.
Question 20
1 mark · Normal
Answer and check →Which change would increase the output voltage of a transformer, assuming the input voltage stays the same?
- A.Increase the number of turns on the secondary coil
- B.Decrease the number of turns on the secondary coil
- C.Increase the number of turns on the primary coil
- D.Use d.c. instead of a.c.