Very Short Answer Questions - 1 Mark

Que 1. What happens if a current carrying conductor is placed in the magnetic field?

Ans. The conductor experiences a force and the direction of this force is given by Fleming's left hand rule.

Que 2. On what effect of an electric current does an electromagnet work? 

Ans. electromagnet works on the magnetic effect of current.

Que 3. Name the alloy which is mainly used for making permanent magnets.

Ans. The alloy 'Alnico' is used for making permanent magnets. It is an alloy of aluminium, nickel, cobalt and iron.

Que 4. Why is electromagnetic induction so called?

Ans. This is due to the reason that electric current can be produced with the help of varying magnetic field without any physical contact of the source of magnetic field and the conductor.

Que 5. Name an instrument in which the directive property of a magnet is used.

Ans. A compass needle.

Que 6. What is a solenoid?

Ans. Solenoid is a coil of many turns of wire, wrapped in the shape of a cylinder.

Que 7. Which effect of electric current is utilised in the working of an electric fuse?

Ans. An electric fuse works on the heating effect of current.

Que 8. what is the frequency of А.С. (alternating current) in India?

Ans. It is 50 Hz.

Que 9. What will you do if you see a person coming in contact with a live wire?

Ans. Such a person should be provided with an insulated support like wood, plastic or rubber in order to disconnect the person from wire.

Que 10. How can it be proved that a magnetic field exists around a current carrying metallic wire?

Ans. When a magnetic compass needle is placed close to the current carrying wire, it will get deflected.

Que 11. How is the strength of the magnetic field at a point near a wire related to the strength of the electric current flowing in the wire?

Ans. The magnitude of magnetic field is directly proportional to the strength of the electric current flowing in the wire.

Que 12. How is the fuse connected in an electric circuit?

Ans. Fuse is connected in series in the circuit.

Que 13. Why is a fuse usually made of tin or tin-copper alloy?

Ans. A fuse is usually made of tin or tin-copper alloy because it has low melting point.

Que 14. What is the capacity of a fuse commonly used in domestic electrical fittings.

Ans. Fuses of capacity 5 ampere or 15 ampere are commonly used in domestic electrical fittings.

Que 15. Name the device used to protect the electric circuits from overloading and short circuiting.

Ans. A fuses are used to protect circuits from overloading and short circuiting.

Que 16. On which effect of electricity does fuse work?

Ans. Heating effect of current.

Que 17. What kind of magnetic field is produced by a current carrying solenoid?

Ans. The magnetic field produced by a current-carrying solenoid is similar to the magnetic field
produced by a bar magnet.

Que 18. Show, with the help of a diagram, the nature of field lines of magnetic field around a current carrying straight conductor.

Ans.

              

Que 19. State Faraday's law of electromagnetic induction.

Ans. Whenever the magnetic field lines linked with a coil change due to relative motion of a magnet and the coil, an induced current is produced in the coil. The magnitude of induced current is directly proportional to the rate of change of magnetic field lines.

Que 20. The frequency of alternating current in India is 50 Hz. What does it mean? 

Ans. In India, the alternating current changes direction after every  second, so the frequency of alternating current is 50 Hz. 

Que 21. Name the scientist who discovered the relationship between electric current and magnetic field.

Ans. Danish physicist, HC. Oersted established the relation between electricity and magnetism.

Que 22. What does the closeness of field lines in a magnetic field signify?

Ans. The degree of closeness of the field lines in a magnetic field indicates the strength of magnetic field in the region.

Que 23. Name the device which converts mechanical energy into electrical energy.

Ans. Electric generator.

Que 24. Which type of generator is used at power stations?

Ans. AC generator.

Que 25. Does the AC generator have any slip ring?

Ans. The AC generator has two slip rings.

Que 26. What is the frequency of DC?

Ans. Zero.