Pearson Edexcel International GCSE (9–1) · PHYSICS · Chapter
Electromagnetic Induction
61 practice questions
Topics covered
Practice questions
21–30 of 61
Question 21
2 marks · Easy
Answer and see the solution →Explain briefly why a transformer is needed to distribute electricity over long distances.
Question 22
3 marks · Easy
Answer and see the solution →A transformer used for a phone charger has 500 turns on its primary coil and 100 turns on its secondary coil. The input voltage is 230 V.
(a)[1 mark]Is this transformer step-up or step-down? State why.
(b)[2 marks]Calculate the output voltage.
Question 23
1 mark · Easy
Answer and see the solution →Name the two main types of transformers used in the transmission of electricity.
Question 24
4 marks · Normal
Answer and see the solution →A transformer has 150 turns on its primary coil and 450 turns on its secondary coil. The input alternating voltage is 12 V.
Calculate the output voltage across the secondary coil.
Question 25
3 marks · Normal
Answer and see the solution →Explain why transformers cannot be used with direct current (d.c.).
Question 26
1 mark · Normal
Answer and see the solution →Which part of a transformer links the magnetic field between the two coils?
- A.Plastic casing
- B.Copper wires
- C.Soft iron core
- D.Steel rod
Question 27
4 marks · Normal
Answer and see the solution →A step-down transformer is used to supply 6 V to a device. The primary coil has 240 turns and the secondary coil has 40 turns. What is the input voltage supplied to the primary coil?
Question 28
3 marks · Normal
Answer and see the solution →The table shows data for four transformers. Complete the table by filling in the missing voltages using the transformer equation.
Primary voltage (V) Secondary voltage (V) Primary turns Secondary turns 15 300 600 9 450 150 6 80 40 Question 29
4 marks · Normal
Answer and see the solution →Figure 1 shows a transformer used to supply power to a small device.
Figure 1. Transformer structure. (a)[1 mark]Label the primary and secondary coils on Figure 1.
(b)[3 marks]Explain why the core is made from soft iron and not another material.
Question 30
4 marks · Normal
Answer and see the solution →The primary coil of a transformer is supplied with 230 V and there is a current of 0.1 A in the primary. If the secondary voltage is 23 V, and the transformer is 100% efficient, calculate the secondary current.