Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Magnetism and Electromagnetism
293 practice questions
Topics covered
Practice questions
121–130 of 154 · Normal
Question 121
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 122
3 marks · Normal
Answer and see the solution →Explain why transformers cannot be used with direct current (d.c.).
Question 123
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 124
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 125
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 126
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 127
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.
Question 128
3 marks · Normal
Answer and see the solution →A transformer has an input voltage of 240 V and an input current of 0.50 A. The transformer is 100% efficient. The output voltage is 12 V.
(a)[3 marks]Calculate the current in the output circuit.
Question 129
2 marks · Normal
Answer and see the solution →A student suggests using a transformer with a direct current (d.c.) supply.
(a)[2 marks]Explain why a transformer does not work with d.c.
Question 130
3 marks · Normal
Answer and see the solution →A step-down transformer has a primary input voltage of 120 V and a primary input current of 0.25 A. The transformer is 100% efficient, and the output voltage is 24 V. Calculate the output current of the transformer.