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#### Magnetism and Electromagnetism Book Back Questions

9th Standard

Reg.No. :
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Science

Time : 00:45:00 Hrs
Total Marks : 30
3 x 1 = 3
1. Which of the following converts electrical energy into mechanical energy?

(a)

motor

(b)

battery

(c)

generator

(d)

switch

2. An electric generator converts

(a)

electrical energy into mechanical energy

(b)

mechanical energy into heat energy

(c)

electrical energy into electrical energy

(d)

mechanical energy into electrical energy

3. The unit of magnetic flux density is

(a)

weber

(b)

weber/metre

(c)

weber/metre2

(d)

weber. metre2

4. 2 x 1 = 2
5. No force acts in a current carrying conductor when it is ________o the magnetic field.

()

parallel

6. Devices which is used to convert high alternating current to low alternating current

()

transformers

7. 3 x 2 = 6
8. State Fleming’s Left Hand Rule.

9. List the main parts of an electric motor.

10. Differentiate step up and step down transformer.

11. 3 x 3 = 9
12. State Faraday’s laws of electromagnetic induction.

13. A current carrying conductor of certain length, kept perpendicular to the magnetic field experiences a force F. What will be the force if the current is increased four times, length is halved and magnetic field is tripled?

14. A transformer is designed to give a supply of 8 V to ring a house bell from 240 V ac mains. The primary coil has 4800 turns. How many turns will be in the secondary coil.

15. 2 x 5 = 10
16. Explain the principle, construction and working of a dc motor

17. Draw a neat diagram of an AC generator.