Class 10th Physics Unit 15 Electromagnetism MCQs Short Long Notes

physics 10th notes ch 15

1. Shape of magnetic lines of force in straight conductor are

 
 
 
 

2. The magnetic lines of force can be traced on cardboard by using

 
 
 
 

3. The Coil of transformer in which alternating voltage is induced is known as

 
 
 
 

4. The number of magnetic lines of force passing through any surface

 
 
 
 

5. ____________ is a study of magnetic effects of current: 

 
 
 
 

6. Which is an electric switch that opens and closes under the control of another electrical circuit?

 
 
 
 

7. Type of transformer which is used to increase the value of alternating voltage

 
 
 
 

8. A generator is a ____ with its inputs and outputs reversed

 
 
 
 

9. Micheal Faraday belonged to _______

 
 
 
 

10. The magnetic field produced in straight current carrying conductor is weaker

 
 
 
 

11. A device which is used to convert electrical energy into rotational kinetic energy

 
 
 
 

12. Number of turns on the primary coil is represented as

 
 
 
 

13. If the Current is induced in a circuit due to change of current in an other circuit, this process is known as

 
 
 
 

14. Force on current carrying conductor in a magnetic field is found by

 
 
 
 

15. Who found the direction of induced e.m.f first time? 

 
 
 
 

16. A device used to convert mechanical energy into electrical energy

 
 
 
 

17. Which thing work on the phenomenon of electromagnetic induction in hydroelectric power plant?

 
 
 
 

18. Magnetic field in most part of the coil is

 
 
 
 

19. According to Faraday’s law of induced emf is ____proportional to change in flux

 
 
 
 

20. Transformer works on the principle of

 
 
 
 

21. Magnetic lines of force in solenoid are

 
 
 
 

22. Number of turns on secondary coil is

 
 
 
 

23. Voltage of current supplied to consumers is

 
 
 
 

24. The coil of transformer in which change in current produces induced current in another coil is known as

 
 
 
 

25. If the current through a coil or a circuit changes and this change induces an emf in the circuit itself, this process is known as

 
 
 
 

26. The coil which is connected to the alternating voltage whose value is to be altered is known as

 
 
 
 

27. If the current is flowing from bottom to top then the direction of magnetic lines of force will be

 
 
 
 

28. Magnetic field of coil Is identical to field of ________ magnet. 

 
 
 
 

29. Who discovered the phenomenon of electromagnetic induction? 

 
 
 
 

30. A transformer has 100 turns in primary and 500 turns in the secondary. If 6 Volts D.C is applied across its primary, the voltage induced across its secondary would be

 
 
 
 

31. Transformer is used to

 
 
 
 

32. Which part of DC motor reverses the direction of current through coil every half cycle?

 
 
 
 

33. When a straight current carrying conductor is placed in a magnetic field at right angle to it, the direction of force acting on conductor is

 
 
 
 

34. Types of transformer are

 
 
 
 

35. Hold down the end of the current carrying solenoid in front of you, if the direction of current flow through this end is anti-clock wise it would be

 
 
 
 

36. Who discovered left hand rule?

 
 
 
 

37. Electromagnet is used in device

 
 
 
 

38. Step down transformer

 
 
 
 

39. The value of induced emf is directly proportional to the rate of change of

 
 
 
 

40. An electrical device which is used to increase or decrease the value of alternating voltage

 
 
 
 

41. A practical application of mutual induction is

 
 
 
 

42. MRI stands for

 
 
 
 

43. Direction of magnetic lines of force in straight conductor is found by

 
 
 
 

44. Transformer is used to change the value of

 
 
 
 

45. Law of electromagnetic induction and electrolysis were presented by

 
 
 
 

46. The polarity of current carrying solenoid is found by

 
 
 
 

47. Electromagnetic induction was discovered by

 
 
 
 

48. The magnetic field produced in straight current carrying conductor is stronger: 

 
 
 
 

49. The magnitude of induced emf depends upon the speed of

 
 
 
 

50. A closely wound cylindrical coil of insulated wire is

 
 
 
 

51. If the current is flowing from top to bottom then the direction of magnetic lines of force will be

 
 
 
 

52. Weak ionic current that travel along the nerve can produce the 

 
 
 
 

53. Transformer is called step-down when

 
 
 
 

54. Lines of force in solenoid resemble the pattern of lines of force due to

 
 
 
 

55. When current passes through straight conductor it produce magnetic field in the form of: 

 
 
 
 

56. In step-up transformer

 
 
 
 

57. A coil in which current is induced is known as

 
 
 
 

58. Which device is based on the principle of electromagnetism?

 
 
 
 

59. Type of transformer which is used to decrease the value of alternating voltage

 
 
 
 

60. In D.C motor coil can rotate in magnetic field by an angle of

 
 
 
 

61. Hold down the end of the current carrying solenoid in front of you, if the direction of current flow through this end is clockwise it would be

 
 
 
 

62. A generator works on the principle of

 
 
 
 

63. Who discovered that when current passes through a conductor it produces a magnetic field around it

 
 
 
 

Short Questions

A conductor wire generates a voltage while moving through a magnetic field. In what direction should the wire be moved, relative to the field to generate the maximum voltage?
Can a transformer operate on direct current?
Can a transformer work on D.C? 
Define A.C. Generator.
Define electromagnetic induction. 
Define ideal transformer.
Define mutual induction.
Define self-Induction.
Define step down transformer and step up transformer. 
Define transformer. 
Explain working principle of relay circuit.
How electricity is produce by electromagnetic induction? 
How magnetic lines of force are formed in the straight current carrying conductor?
How voltages are stepped down? 
Illustrate diagrammatically the similarity between magnetic field of a bar magnet and that of a coil.
Is it possible that a constant current flowing in a coil produces an induced current in another coil?
Prove that Lenz law is a manifestation of the law of conservation of energy. 
State and explain the rule by which the direction of the lines of force of the magnetic field around a current-carrying conductor can be determined. 
State Faraday law of Electromagnetic Induction.
State Fleming’s Left Hand Rule.
State Lenz’s law?
Suppose someone handed you three similar iron bars and told you one was not magnet, but the other two were. How would you find the iron bar that was not magnet?
Suppose we hang a loop of wire so that it can swing easily. If we now put a magnet into the coil, the coil will start swinging. Which way will it swing relative to the magnet, and why?
Suppose you have a coil of wire and a bar magnet. Describe how you could use them to generate an electric current.
What is the difference between a generator and a motor?
What reverses the direction of electric current in the armature coil of D.C motor?
What are the factors which increase force on a current carrying conductor?
What are uses of transformer? 
What do you know about primary coil and secondary coil? 
What do you understand by the term mutual induction?
What factors affect induced emf? 
What is difference between magnetism and electricity? 
What is meant by strength of magnetic field? When it is maximum and minimum?
What is relay circuit?
What is Right Hand Grip Rule?
What is Solenoid?
What is the function of core in the transformer?
What is working principle of transformer? 
When a straight current-carrying conductor is placed in a magnetic field, it experiences a force. State the rule by which the direction of this force can be found out.
When the force on the current carrying conductor in a magnetic field is maximum and when it is minimum?
Which device is used for converting electrical energy into mechanical energy?
Which device convert mechanical energy into electrical energy in hydroelectric dam?
Why alternating voltage is stepped up at the generating station?
Write down the principle of A.C. generator
Write down the rules to find the polarity of solenoid. 
You are given an unmarked magnetized steel bar and bar magnet, its north and south ends are marked N and S respectively. State how would you determine the polarity at each end of the unmarked bar?

Long Questions

A power station generates 500 MW of electrical power which is fed to a transmission line. What current would flow in the transmission line, if the input voltage is 250 kV?
A step-down transformer has a turns ratio of 100 : 1. An ac voltage of amplitude 170 V is applied to the primary. If the current in the primary is 1.0 mA, what is the current in the secondary?
A step-up transformer has a turn ratios of 1 : 100. An alternating supply of 20 V is connected across the primary coil. What is the secondary voltage?
A transformer is needed to convert a mains 240 V supply into a 12 V supply. If there are 2000 turns on the primary coil, then find the number of turns on the secondary coil.
A transformer, designed to convert the voltage from 240 V a.c mains to 12 V, has 4000 turns on the primary coil. How many turns should be on the secondary coil? If the transformer were 100% efficient, what current would flow through the primary coil when the current in the secondary coil was 0.4 A?
Briefly write about the high voltage transmission.
Demonstrate by an experiment that a magnetic field is produced around a straight current-carrying conductor .
Describe a simple experiment to demonstrate that a changing magnetic field can induce e.m.f. in a circuit.
Describe the direction of an induced e.m.f. in a circuit? How does this phenomenon relate to conservation of energy?
Draw a labelled diagram to illustrate the structure and working of A.C generator .
State and explain the rule by which the direction of the lines of force of the magnetic field around a current-carrying conductor can be determined.
State that a current-carrying coil in a magnetic field experiences a torque.
State Faraday’s law. How the direction of induced e.m.f is determined by Len’s law?
The voltage chosen for the transmission of electrical power over large distances is many times greater than the voltage of the domestic supply. State two reasons why electrical power is transmitted at high voltage.
What is a transformer? Explain the working of a transformer in connection with mutual induction.
What is an electric motor? Explain the working principle of D.C motor .
What are the factors which affect the magnitude of the e.m.f. induced in a circuit by a changing magnetic field?
What do you understand by the term mutual induction? Name and Define SI unit of mutual inductance?
What is electromagnetic induction? Describe simple experiments to demonstrate that a changing magnetic field can induce an e.m.f in a circuit?
Write applications of electromagnet.
Write the working of AC generator. How current is produced from a generator?

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