Magnetism Exercise 10b
Please Select
Q1 What is an electromagnet?
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Q2 Name the material used for preparing an electromagnet.
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Q3 How is an electromagnet made? Name two factors on which the strength of the magnetic field of an electromagnet depends.
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Q4 You are required to make an electromagnet from a soft iron bar by using a cell, an insulated coil of copper wire and a switch. (a) Draw a circuit diagram to represent the process. (b) Label the poles of the electromagnet.
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Q5 Figure shows a coil wound around a soft iron bar XY. (a) State the polarity at the end X and Y as the switch is pressed. (b) Suggest one way of increasing the strength of the electromagnet so formed.
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Q6 A coil of insulated copper wire is wound around a piece of soft iron and current is passed in the coil from a battery. What name is given to the device so obtained? Give one use of the device mentioned by you.
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Q7 Show with the aid of a diagram how a wire is wound on a U-shaped piece of soft iron in order to make it an electromagnet. Complete the circuit diagram and label the poles of the electromagnet.
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Q8 State two ways through which the strength of an electromagnet can be increased.
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Q9 Name one device that uses an electromagnet.
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Q10 State two advantages of an electromagnet over a permanent magnet.
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Q11 State two differences between an electromagnet and a permanent magnet.
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Q12 Why is soft iron used as the core of the electromagnet in an electric bell?
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Q13 How is the working of an electric bell affected, if alternating current is used instead of direct current?
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Q14 Name the material used for making the armature of an electric bell. Give a reason for your answer.
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Multiple Choice Questions
Q1 Electromagnets are made up of:
(a) steel
(b) copper
(c) soft iron
(d) aluminum
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Q2 The strength of an electromagnet can be increased by:
(a) reversing the directions of current
(b) using alternating current of high frequency
(c) increasing the current in the coil
(d) decreasing the number of turns of coil
Solution :
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