#### Electricity Model Question Paper

7th Standard EM

Reg.No. :
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Science

Time : 01:30:00 Hrs
Total Marks : 50
4 x 1 = 4
1. The direction of conventional current is ------------------ to electron flow.

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2. ------------------ is used to measure the electric current.

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3. In conducting materials electrons are ------------------ bounded with atoms.

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4. S.I. unit of Electrical conductivity of a conductor is --------------------

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5. 3 x 1 = 3
6. Electron flow is in the same direction to conventional current flow.

(a) True
(b) False
7. The fuse wire does not melts whenever there is overload in the wiring.

(a) True
(b) False
8. The representation of the electric current is A.

(a) True
(b) False
9. 5 x 1 = 5
10. Cell

11. (1)

A complete path for the flow of an electric current

12. Switch

13. (2)

used to open or close a circuit

14. Circuit

15. (3)

safety device used in electric circuit

16. Miniature circuit Breaker

17. (4)

Reset by hand, circuit becomes complete once again

18. Fuse

19. (5)

A device which converts chemical energy into electrical energy

1 x 2 = 2
20. Assertion (A): Insulators do not allow the flow of current through themselves.
Reason (R) : They have no free charge carriers.
A. If both A and R are true and the R is correct explanation of A.
B. If both A and R are true but R is not a correct explanation of A.
C. If A is true and R is false.
D. If both A and R are false.

21. 4 x 2 = 8
22. Water : pipe : : Electric current :-------------

23. Copper : conductor : : Wood : ---------------

24. Length : metre scale : : Current : ------------

25. milli ampere: micro ampere : : 10-3A : ------

26. 2 x 2 = 4
27. Three conductors are joined as shown in the diagram
The current in conductor RS is 10 A. The current in conductor QR is 6 A. What will be the current in conductor PR

a) 4 A
b) 6 A
c) 10 A
d) 16 A

28. Study the electric circuit below. Which of the following switches should be closed so that only two bulbs will light up
a) S1,S2 and S4 only
b) S1, S3 and S5 only
c) S2, S3 and S4 ony
d) S2, S3 and S5 only

29. 4 x 2 = 8
30. What is the speed of electric current?

31. Define fuse.

32. Name few insulators

33. What is a battery?

34. 2 x 3 = 6
35. Define an electric current.

36. Define electrical conductivity.

37. 2 x 5 = 10
38. Explain the construction and working of an Telephone.

39. Explain the construction and working of a dry cell.