Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Electromagnetism
68 practice questions
Topics covered
Practice questions
31–35 of 35 · Normal
Question 31
4 marks · Normal
Answer and see the solution →Draw a labelled diagram of a transformer. Include the following labels: primary coil, secondary coil, soft iron core, input (AC supply), and output.
Question 32
6 marks · Normal
Answer and see the solution →An electric motor uses electromagnets and is connected to the National Grid.
(a)[3 marks]Describe how an electric current in a coil produces a force, and explain how this makes the coil rotate in an electric motor.
(b)[3 marks]Transformers are used in the National Grid. Explain why step-up transformers are used to transmit electricity from power stations.
Question 33
5 marks · Normal
Answer and see the solution →A coil of wire is moved quickly through a magnetic field in a generator, which is connected to a step-down transformer.
(a)[2 marks]Describe how electromagnetic induction occurs in the coil when it is moved through the magnetic field.
(b)[1 mark]Explain how changing the speed of movement of the coil affects the size of the induced voltage.
(c)[2 marks]A step-down transformer connected to the generator has 3000 turns on its primary coil and 600 turns on its secondary coil. The input voltage to the primary is 240 V a.c. Calculate the output voltage of the secondary coil.
Question 34
5 marks · Normal
Answer and see the solution →A solenoid is used as an electromagnet and is part of a moving-coil loudspeaker. The speaker is powered by an alternating current produced by a generator.
(a)[2 marks]Describe the magnetic field pattern produced around a solenoid when current flows through it.
(b)[2 marks]Explain why the core of the solenoid in an electromagnet should be made from iron and not steel.
(c)[1 mark]Explain briefly how the movement of a generator's coil produces an alternating current to power the speaker.
Question 35
5 marks · Normal
Answer and see the solution →A power station uses large generators and transformers to supply electrical energy to homes.
(a)[2 marks]Explain why the electricity generated by the power station must pass through step-up transformers before long-distance transmission.
(b)[2 marks]A step-up transformer has 120 turns on its primary coil and 2,880 turns on its secondary. If the input voltage is 11,000 V a.c., calculate the output voltage.
(c)[1 mark]Describe one danger associated with transmitting electricity at high voltages.