Magnetic effect of current Worksheet-7

Magnetic effect of current Worksheet-7

1. What is the force acting on charge (q) moving in a direction perpendicular to a magnetic field (B) with velocity v ?

2. Which rule do we use to find the direction of this force ?

3. What is electromagnetic induction ?

4. What do you mean by magnetic flux ?

5. Name the rule which gives the direction of induced current?

6. Name the device which converts mechanical energy into electrical energy.

7. What type of dynamo is used in a bicycle ?

8. What type of dynamo is used in industry ?

9. What type of current is given by a cell ?

10. What type of current is used in household supply ?

11. How is AC different from DC ?

12. Name the two types of wiring systems used in domestic circuits,

13. Which effect of electric current is used in the working of an electric fuse ?

14. Of what substance is a fuse wire made of ?

15. What is the capacity of an electric fuse used in (i) lighting circuit (ii) power circuit in household supply?

16. Why is a fuse wire made of tin-lead alloy ?

17. Where do we connect a fuse : with live wire or with neutral wire ?

18. What are the colours of live, neutral and earth wires ?

19. What should be done in case a person comes in contact with a live wire ?

20. State Right-Hand Thumb Rule to find the direction of magnetic field around a straight conductor carrying current. How will this magnetic field be affected on :

(a) increasing the current through the conductor,

(b) changing the direction of flow of current through the conductor ?

Answer:

1. F = q v B.

2. Fleming's left-hand rule.

3. It is the phenomenon of producing induced current in a closed circuit by changing magnetic flux linked with it.

4. The total number of magnetic field lines linked with a circuit is called magnetic flux.

5. Fleming's right-hand rule.

6. Electric generator or dynamo.

7. We use a DC dynamo in a bicycle.

8. In industry, AC dynamo is used.

9. The current given by cell is DC.

10. Household supply uses AC.

11. The direction and magnitude of AC change periodically whereas in case of DC, these remain constant.

12. (i) Tree system (ii) Ring system.

13. Heating effect of current.

14. An alloy of lead (75%) and tin (25%).

15. (i) 5 A (ii) 15 A.

16. This alloy has a low melting point.

17. With live wire.

18. Red, black and green.

19. The person should be provided with an insulated support like dry wood, plastic or rubber so that the current stops flowing through his body.

Hold the straight conductor in your right hand such that the thumb points out in the direction of flow of current. The direction of curling of the fingers gives the direction of the magnetic field lines around the conductor.

(a) increasing current through the conductor increases the strength of the magnetic field.

(b) changing the direction of flow of current through the conductor changes the direction of the magnetic field. In any case the strength of the magnetic field remains the same.