Class 7 Science Chapter 10 Electric Current And Its Effects Quiz 4 (60 MCQs)

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1. A straight wire carrying a 9.0 A current is in a uniform magnetic field oriented at right angles to the wire. When 75 cm of wire is in the field, the force on the wire is 1.2 N. What is the strength of the magnetic field (B)? HINT:F=I.L.B
2. In most electrical circuits, the pathway is made of:
3. A bell only rings one time when switched on (The gong is hit only one time) because-
4. In electromagnetic induction, the direction of the induced current is given by:
5. Unlike poles of a magnet do what?
6. A path that is made for an electric current is?
7. Which of the following is/are the applications of Electrolysis?
8. To make a battery the terminals of two cells should be placed such that
9. Which of the following liquid is not a good conductor of electricity?
10. The following is the formula for ..... F$_{e}$ = q x E
11. Use and throw fuse is?
12. The coil of wire used in Electric Heaters is called as .....
13. What is true about electricity and magnetic fields?
14. How much current is produced in an electric iron consumes energy at a rate of 880 W with the voltage is 220 V?
15. Explain the chemical effects of electric current with an example.
16. The process of depositing a layer of desired metal on another metal
17. Who was the first person to notice the deflection of compass needle everytime the current was passed through a wire kept nearby?
18. What happens when the circuit is open?
19. Electric bell works on ..... effect of current
20. In a uniform magnetic field the field, lines are:
21. Which of the following appliances is not based on the principle of heating effect of electric current?
22. The average relaxation time during collision of electrons with atoms is
23. Substances that conduct electricity are called .....
24. What is found in the nucleus of an atom?
25. Electric kettles and radiators use the effect of current flow known as:
26. Directions of drift velocity of electrons and electric field are
27. What device changes mechanical kinetic energy into electrical energy?
28. Current in an electric circuit can exceeds it's maximum limit when,
29. Ordinary cells used in torches are .....
30. Like poles of a magnet do what?
31. The direction of induced current is determined by:
32. The North pole of Earth's magnetic field is in the:
33. Why is LED preferred to other type of bulbs?
34. What happens to the strength of the magnetic field when the current through a wire is increased?
35. Which of the following phenomenon occurs when two naked wires of electricity supply line touch each other?
36. Rechargeable batteries are batteries that can have their internal chemical reaction:
37. Metal which is electroplated on car parts such as bumpers.
38. The symbol used to express the current is .....
39. A basic voltaic cell consists of two different metal electrodes immersed in an electrolyte.
40. In fleming's left hand rule the fore finger denotes the direction of .....
41. An electric motor is a device which transforms:
42. The S.I. unit of magnetic field is:
43. What is the relationship between Rubber and Insulator?
44. What is the primary difference between a series circuit and a parallel circuit?
45. What are conductors in the context of electricity?
46. Who discovered the magnetic field of electric current?
47. All liquids conduct electricity.
48. The sure test of magnetism is:
49. The device which transfers energy to electric charges in a circuit is
50. Which of these charges has the greatest magnitude?
51. If the number of turns in the coil of an electromagnet is more, the strength of the electromagnet will be
52. Element of an electric iron is made up of
53. Can we magnetise an iron object with electromagnet
54. Radhika wants to electroplate a plate with ZINC. She has a Zinc bar and the plate. But she does not know which should be the anode and which should be the cathode.
55. What is a cation's charge?
56. Who invented MAGNETIC EFFECT OF ELECTRIC CURRENT?
57. A combination of two of more cells is known as
58. The direction of current flow is taken from
59. Which of the following statements is incorrect about the conductivity of water?
60. What happens when an electric current is passed through an electrolyte?