2nd Year Physics Chapter 14 Electromagnetism Notes MCQs Solutions

physics 12th notes mcqs chapter 14

1. If the magnetic flux is expressed in weber, then the magnetic induction can be expressed as:

 
 
 
 

2. An AVO meter is also called

 
 
 
 

3. SI unit of magnetic flux is (one Weber is equal to)

 
 
 
 

4. SI unit of magnetic flux density is

 
 
 
 

5. A sensitive galvanometer measures currents:  

 
 
 
 

6. The direction of magnetic lines of force are depend upon:

 
 
 
 

7. A device used for the detection of current is called

 
 
 
 

8. The magnetic force experienced by a charged particle moving in a magnetic field will be maximum when it moves:

 
 
 
 

9. An avomneter can also be called as

 
 
 
 

10. The SI unit of magnetic induction tesla is equal to

 
 
 
 

11. tesla is a unit of:

 
 
 
 

12. The electron will be deflected

 
 
 
 

13. Magnetic flux density at a point due to the current carrying conductor determined by:

 
 
 
 

14. The force which deflects the coil of the galvanometer is called:

 
 
 
 

15. Nm/A is commonly called:

 
 
 
 

16. To convert a galvanometer into an ammeter, the shunt
resistance is given by

 
 
 
 

17. If the number of turns become double but length remain same, then magnetic field in the solenoid become

 
 
 
 

18. Which one among the following material is most suitable for making core of electrometer:

 
 
 
 

19. The direction of magnetic lines of force around a current carrying conductor is given by:

 
 
 
 

20. When the charge particle is projected in the direction parallel to the magnetic field, then force experienced will be:

 
 
 
 

21. When a charge is projected perpendicular to a uniform magnetic field, its path is:

 
 
 
 

22. If a charge of one coulomb moving at right angle to a magnetic field with a velocity of one meter per second experiences a
force of one Newton , the magnetic induction is said to be

 
 
 
 

23. Weber has the dimensions of:                 

 
 
 
 

24. In CRO, there are: 

 
 
 
 

25. The voltage applied across Y-plate deflects the beam:

 
 
 
 

26. The magnetic field at a point due to current carrying conductor is directly proportional to which among the following:

 
 
 
 

27. The charge moving perpendicular to B experiences

 
 
 
 

28. The magnitude of permeability of free space is

 
 
 
 

29. Shupted galvanometer is called.

 
 
 
 

30. Energy stored per unit volume inside a solenoid is called as;

 
 
 
 

31. When an electron enters at right angle to the magnetic field, the magnitude of velocity:

 
 
 
 

32. A magnetic compass will be defected ifit is kept near a:

 
 
 
 

33. A magnetic field:

 
 
 
 

34. A changing magnetic field produces:

 
 
 
 

35. A galvanometer is converted into an ammeter by connecting a
suitable

 
 
 
 

36. A proper combination of a galvanometer and a series of resistance act as:

 
 
 
 

37. Ammeter is a —- instrument

 
 
 
 

38. Such a galvanometer in which the coil comes to rest quickly after
the current passed through it is called

 
 
 
 

39. Amperean path is:             

 
 
 
 

40. The name of the scientist who noted that a compass needle was deflected when placed near the current carrying conductor:

 
 
 
 

41. The charges moving perpendicular to magnetic field experience force

 
 
 
 

42. When a particle of charge q and mass m enters a region at constant magnetic induction B, traveling with the velocity Perpendicular to the direction of the field, it describes a circular orbit of radius

 
 
 
 

43. The electron gun in cathode ray oscilloscope consists of:

 
 
 
 

44. If the length of the solenoid is doubled without changing the number of turns then magnetic field:

 
 
 
 

45. In CRO, the output waveform of time base generator is:

 
 
 
 

46. A compass needle will be deflected if it is kept near:

 
 
 
 

47. When an electric charge q is placed in an electric field, it will experienced a force:

 
 
 
 

48. The device used for displaying the waveform of given voltage is:

 
 
 
 

49. The energy resides in a current carrying conductor in the form of what among the following:

 
 
 
 

50. If there are n charge carriers per unit volume then the number of charge carriers in a segment of wire of length L and area A is:

 
 
 
 

51. The grid in CRO

 
 
 
 

52. The unit of magnetic induction B is:

 
 
 
 

53. A moving coil galvanometer can be converted into ammeter by connecting choose which one is correct:

 
 
 
 

54. The coil of galvanometer is suspended in a radial magnetic field
so that the deflecting torque on the coil is

 
 
 
 

55. The magnetic force experienced by a charge particle moving in a magnetic field will be maximum when it moves:

 
 
 
 

56. In order to increase the range of a voltmeter, series resistance is

 
 
 
 

57. Which one of the following is the unit of magnetic induction:

 
 
 
 

58. Lorentz force means the force acting on a particle, which is:

 
 
 
 

59. The magnetic field inside the solenoid can be increased by:  

 
 
 
 

60. Magnetic induction is defined as flux per unit area of the surface, which is:

 
 
 
 

61. Charge to mass ratio (e/m) of a charged particle is also called:

 
 
 
 

62. Two lines of magnetic force

 
 
 
 

63. When a charged particle is projected perpendicular to magnetic
field its trajectory is

 
 
 
 

64. Resistance of a voltmeter should be as compared to the resistance across with it is connected.

 
 
 
 

65. A charged particle enters in a strong magnetic field, its K.E.

 
 
 
 

66. Force on a charged particle is zero when projected at angle with the magnetic field:

 
 
 
 

67. Indirectly heated cathode means that the:

 
 
 
 

68. Magnetic flux density at any point due to a current carrying conductor can be computed from:

 
 
 
 

69. Magnetic induction is called

 
 
 
 

70. A device used for the measurement and detection of current is called:

 
 
 
 

71. The total no of magnetic lines of force passing normally through a given area will be known ad:

 
 
 
 

72. The cathode ray oscilloscope is useful for:

 
 
 
 

73. In the formula, B = gonl, where n represents:

 
 
 
 

74. What will be the strength of magnetic field around a conductor :

 
 
 
 

75. If a high resistance is connected in series to a galvanometer, then galvanometer is converted into

 
 
 
 

76. A galvanometer is converted into an voltmeter by connecting a
suitable

 
 
 
 

77. An avometer is also called:

 
 
 
 

78. Two free parallel wires carrying currents in opposite direction:

 
 
 
 

79. The magnetic force experienced by a charge particle moving in a magnetic field will be minimum when it moves:

 
 
 
 

80. The function of grid in cathode ray oscilloscope is:

 
 
 
 

81. A long tightly wound cylindrical coil of wire is called:

 
 
 
 

82. Cathode ray oscilloscope works by deflecting a beam of:

 
 
 
 

83. The SI unit of magnetic flux density is

 
 
 
 

84. One Henry is equal to:

 
 
 
 

85. The magnetic force is simply a:

 
 
 
 

86. A solenoid is a coil of wire, which is:

 
 
 
 

87. A current carrying conductor is placed in a magnetic field. How
must it be oriented such that force on it is zero

 
 
 
 

88. The sensitivity of a galvanometer is given by

 
 
 
 

89. The direction of the magnetic field produced by a linear current is given by:

 
 
 
 

90. In case of galvanometer, the magnitude of the deflecting torque is given as:

 
 
 
 

91. The SI unit of magnetic induction is

 
 
 
 

92. Weber is unit of

 
 
 
 

93. When a charged particle moves through a magnetic field, the
effect of the field changes the particle’s

 
 
 
 

94. To measure the current in a circuit ammeter is always connected in:

 
 
 
 

95. A current carrying conductor experience maximum magnetic force in a uniform magnetic field when it is placed

 
 
 
 

96. Vector area is vector whose direction is:           

 
 
 
 

97. In order to increase the range of an ammeter, the shunt
resistance is

 
 
 
 

98. The magnetic lines of force are:

 
 
 
 

99. Two parallel wires carrying current in same direction —————
each other

 
 
 
 

100. The magnetic field out of the solenoid is:

 
 
 
 

101. The value e/m is smallest for:

 
 
 
 

102. In the region surrounding a current carrying wire:

 
 
 
 

103. An electron of mass m and charge e moving in a circle of radius r with velocity v in a uniform magnetic field of strength B. then

 
 
 
 

104. The expression B.∆l = µ₀I is known as

 
 
 
 

105. Brightness of spot on screen of oscilloscope is controlled by

 
 
 
 

106. The voltage applied across X-plats deflects the beam:

 
 
 
 

107. The charged particle moving in a magnetic field experiences a
magnetic force given by

 
 
 
 

108. An ammeter only can be used in

 
 
 
 

109. Tesla is the unit for measuring:

 
 
 
 

110. force on charged particle moving parallel to magnetic field is

 
 
 
 

111. The sensitivity of the galvanometer can be increased by increasing the:

 
 
 
 

112. Two parallel straight wires carrying current in opposite direction:

 
 
 
 

113. Which of the following resistance is used to convert a
galvanometer into an ammeter

 
 
 
 

114. The force acting on one metre length of the conductor placed at right angle to the magnetic field is called:

 
 
 
 

115. Torque on a current carrying conductor placed in a uniform
magnetic field is

 
 
 
 

116. The sensitivity of a galvanometer can be increased if the factor c/BAN

 
 
 
 

117. The e/m of an electron can be calculated if we know the value of:

 
 
 
 

118. The magnetic field at a point due to a current carrying
conductor is directly proportional to

 
 
 
 

119. Who discovered a relation between magnetic and electric field:

 
 
 
 

120. When the charge particle is projected at right angles to the magnetic field then force experienced will be:

 
 
 
 

121. Which one of the following particles moving in the magnetic field cannot be deflected?

 
 
 
 

122. The anode in CRO are at:             

 
 
 
 

123. Brightness of screen of CRO controlled by Grid

 
 
 
 

124. SI unit of magnetic flux is

 
 
 
 

125. The coil is situated in the magnetic field such that the plane of
the coil is always

 
 
 
 

126. CRO works by deflecting the beam of electron as they pass through:

 
 
 
 

127. If a charge is at rest in a magnetic field then force on charge is:

 
 
 
 

128. Magnetic field is a:

 
 
 
 

129. Minimum current required to produce a deflection of one mille
meter on a scale at a distance of 1 meter is

 
 
 
 

130. The expression for torque acting on a current carrying coil placed in a uniform magnetic field is equal to:

 
 
 
 

131. If fingers of right show the direction of magnetic field and palm show the direction of force then thumb points for

 
 
 
 

132. Magnetic force acting on unit positive charge moving perpendicular to the magnetic field with a unit velocity is known as:

 
 
 
 

133. A current carrying conductor placed parallel to magnetic field
experiences force

 
 
 
 

134. The strength of magnetic field is measured in SI units:

 
 
 
 

135. How are the electrons produced in a cathode ray oscilloscope:

 
 
 
 

136. Which of the following apparatus is used to measure current,
voltage and resistance

 
 
 
 

137. One tesla is equal to

 
 
 
 

138. Two parallel wires carrying current in the same direction:

 
 
 
 

139. When some compass needles are placed on a cardboard along a circle with the center at the wire, they will:

 
 
 
 

140. Ammeter is used to measure

 
 
 
 

141. Voltmeter is used to measure

 
 
 
 

142. Which one is suitable for circular trajectory of a charged particle:

 
 
 
 

143. Two parallel straight wires carrying current in same direction will 

 
 
 
 

144. Cathode ray oscilloscope works by deflecting beam of

 
 
 
 

145. The permeability of free space is measured in: 

 
 
 
 

146. In current carrying long solenoid the magnetic field produced does not depend upon

 
 
 
 

147. If a current carrying conductor is placed perpendicular to the magnetic field, it will experience a force:

 
 
 
 

148. Magnetic flux in terms of B and area A is

 
 
 
 

149. A current carrying conductor placed perpendicular to magnetic
field experiences force

 
 
 
 

150. The relation between current I and the angle of deflection in a
moving coil galvanometer is

 
 
 
 

151. For accurate measurement of current through a circuit , the
resistance of ammeter should be

 
 
 
 

152. If a moving electron deflected side ways on passing through a certain region of space, can we predict the presence of a magnetic field:

 
 
 
 

153. The magnetic field produced by a current carrying conductor at
a point is B=

 
 
 
 

154. The SI unit of permeability go is:

 
 
 
 

155. which instrument among the following can measure potential without drawing any current is called:

 
 
 
 

156. By means of waveform displayed on the screen of CRO, we can measure:

 
 
 
 

157. Saw toothed waveform means that its voltage:

 
 
 
 

158. The sources of magnetic field are:

 
 
 
 

159. The earth magnetic field always has a vertical component except at the :

 
 
 
 

160. The sensitivity of a galvanometer can be increased by
decreasing

 
 
 
 

161. The S.I unit of permeability of free space is

 
 
 
 

162. When a small resistance is connected parallel to the galvanometer, the resulting is:

 
 
 
 

163. 5m wire carrying a current of 2A is a right angle to the uniform magnetic field of5weber/m² .The force on the wire

 
 
 
 

164. An ideal voltmeter has

 
 
 
 

165. When an electron is projected in a direction perpendicular to the lines of magnetic force, its path may be:

 
 
 
 

166. A current carrying conductor placed in a magnetic field
experiences force

 
 
 
 

167. A current carrying conductor surrounded by:

 
 
 
 

168. If the fingers of right hand show the direction of magnetic field
and palm shows direction of force then thumb points for

 
 
 
 

169. A current carrying conductor is surrounded by

 
 
 
 

170. Magnetic force on a moving charge is minimum when

 
 
 
 

171. Which one of the following quantities can be replaced by magnetic induction:

 
 
 
 

172. Ampere based his circuital law on the findings of:

 
 
 
 

173. The sum of electric and magnetic force is called.

 
 
 
 

174. The current passing through the coil of galvanometer is directly proportional to:

 
 
 
 

175. A galvanometer can be converted into a voltmeter by connecting a what among the following:

 
 
 
 

176. A long wire wound tightly on a cylindrical coil is called:

 
 
 
 

177. Useful device to measure resistance, current and voltage is an electronic instrument called:

 
 
 
 

178. The e/m of an electron moving with speed along a circular path
in a magnetic field is

 
 
 
 

179. The magnetic force is

 
 
 
 

180. A current flowing towards the reader be denoted by:

 
 
 
 

181. Which of the following particles moving in magnetic field would
not be deflected

 
 
 
 

182. Shunt resistance is called

 
 
 
 

183. The magnetic field is uniform and stronger:

 
 
 
 

184. The grides in CRO is at:               

 
 
 
 

185. The galvanometer can be made sensitive by making the factor

 
 
 
 

186. An electron enters a region where the electric field E is
perpendicular to magnetic field B. It will suffer no deflection

 
 
 
 

187. When a small resistance is connected parallel to galvanometer
the resulting is

 
 
 
 

188. When the angle between the vector area and the magnetic field is 00 then magnetic flux is:

 
 
 
 

189. Two parallel wires carrying current in opposite direction ———–
—- each other

 
 
 
 

190. To convert a wheat stone type galvanometer in to voltmeter, the series resistance is (the high resistance connected in series with galvanometer to convert it into voltmeter of range 0-V volt
is given by)

 
 
 
 

191. The force experienced by the conductor is:

 
 
 
 

192. The magnetic field at the middle of the solenoid is:

 
 
 
 

193. What is emitted by the hot metal filament in a cathode ray oscilloscope:

 
 
 
 

194. Magnetic force on a moving charge is maximum when

 
 
 
 

195. If the magnetic field is directed along the normal to the area, then magnetic flux is:

 
 
 
 

196. Magnetic force on a current carrying conductor is maximum
when

 
 
 
 

197. The dot product of magnetic field B and vector area A is:

 
 
 
 

198. The relation B= µ₀I/2πr is called

 
 
 
 

199. One tesla is equal to

 
 
 
 

200. Electric current produces magnetic field was suggested by:

 
 
 
 

Short Questions

1. A current- carrying wire is placed in a magnetic field.How must it be oriented so that the force on it is zero or is maximum?
2. A current in a conductor produces a magnetic field which defined as the rate of flow of charge what can you conclude about the magnetic field due to stationary charges?What about moving charges?
3. A loop of wire is suspended between the poles of a magnet with its plane parallel to the pole faces.What happens if direct current is passed through the coil?What will happen if an alternating current is passed instead?
4. A magnet attracts only a magnet.Explain?
5. A plane conducting loop is located in a uniform magnetic field that is directed along the x-axis.For what orientation of the loop is the flux a maximum?For what orientation is the flux a minimum?
6. A Sensitive galvanometer cannot be stable.Explain why?
7. A wire is covered with a carpet.How will you find whether any current is flowing through the wire?
8. An ammeter and voltmeter of suitable ranges are to be used to measure the current and voltage of an electric lamp.What would happen if by mistake the meters were interchanged?
9. An electron and a proton are made to move at right angles to a given magnetic field with a certain velocity.Which of the particles will suffer greater deflection?
10. An isolated magnetic is not possible How can we have it for some practical purpose ?
11. At a given instant a proton moves in the positive x direction in a region where there is magnetic field in the nagetive z direction.What is direction of the magnetic force?
12. Can a single moving proton produce magnetic field?
13. Can an electron at rest be set in motion with a magnet?
14. Can the field of earth magnetlse a magnetic material?
15. Can two lines of force ever cross each other?
16. Define deflecting couple ?
17. Define magnetic field ?
18. Define torsional couple ?
19. Describe the change in the magnetic field inside a solenoid carrying a steady current I if (a) the length of the solenoid is doubled but the number of turns remains the same and (b) the number of turns is doubled but the length remains the same?
20. Distinguish between flux density and flux.How are they related?
21. Does an ordinary voltmeter measure the potential difference across a resistor quickly?
22. Explain the magnetic filed due to current ?
23. Explain the working principle of CRO ?
24. How behaves a solenoid when current passes through it ?
25. How can a current loop be used to determine the presence of a magnetic field in a given region of space?
26. How can you use a magnetic field to separato isotopes of chemical element?
27. How is the polartity of a solenoid determined?
28. How much of the flux will pass through rectangular coil in case if it held i) Parallel ii) Perpendicular and iii) at an angle of 45ᵒ to the magnetic field?
29. How poles of solenoid can be found ?
30. How the presence of magnetic field is determined around a current carrying conductor ?
31. If a charged particle moves in a straight line through some region of space, can you say that the magnetic field in that region is zero ?
32. If the suspension wire is thin it will have a small value of c when the current passes through the circuit the pointer of the sensitive galvanometer vibrates about its mean position due to small value of c and large value of B,A and N. It comes to rest after vibrating for a longer time.Thus the galvanometer is not stable due to small value of c and large moment of inertia of the pointer.
33. In what direction a charged particle moving in magnetic field experiences a resultant force ?
34. In what direction are the magnetic field lines surrounding a straight wire carrying current that is moving towards you?
35. Is it possible to obtain an isolated north pole?
36. Is it possible to orient a current loop in a uniform magnetic field such that the loop will not tend to rotate?
37. Name the essential parts of a CRO ?
38. Name the main parts of a CRO?
39. State Ampere’s circuital law ?
40. Suppose that a charge q is moving in a uniform magnetic field with a velocity v why is there no work done by the magnetic force that acts on the charge q?
41. Two changed particles are projected into a region where there is a magnetic field perpendicular to their velocities if the charges are deflected in opposite direction what can you say about them?
42. Two wires carrying equal and opposite currents are twisted together in the construction of a circuit.Why does this technique reduce stray magnetic fields?
43. Weather magnetic flux is a scalar quantity or a vector quantity ?
44. What do you understand by DMM?
45. What does AVO mean?
46. What is a relation for the magnetic force on a current carrying conductor in a uniform magnetic field ?
47. What is a relation for the magnetic force on a moving charge in a magnetic field ?
48. What is a Solenoid ?
49. What is an AVO meter ?
50. What is an Ohm-meter ?
51. What is cathode ray oscilloscope ?
52. What is Digital multi-meter ?
53. What is line of magnetic force ?
54. What is Lorentz force ?
55. What is meant by the sensitivity of a galvanometer ?
56. What is moving magnet type galvanometer ?
57. What is right hand rule ?
58. What is shunt resistance?How is it used to convert a galvanometer into an ammeter?
59. What is SI unit of magnetic field and define it ?
60. What is stable or dead beat galvanometer?
61. What is the expression for the ratio charge to mass of an electron ?
62. What is the importance of a hair spring in a Weston galvanometer?
63. What is the important use of a CRO ?
64. What is the lamp and scale arrangement?
65. What is the magnetic field due to current in a solenoid ?
66. What is the resistance measuring part of AVo meter ?
67. What is the sensitivity factor of galvanometer ?
68. What is the value of high resistance Rh required to convert galvanometer into voltmeter ?
69. What is the value of u in Sl units ?
70. What is the working principal of CRO?
71. What is the working principle of a galvanometer?
72. What kind of magnetic field is produced by a straight wire carrying a current?
73. What should be the orientation of a current carrying coil in a magnetic field so that torque acting upon the coil is (a) maximum (b) minimum ?
74. What type of magnetic substance would be prefer for marking permanent magnet ?
75. When a beam of electrons is projected into a certain region of space, the electrons travel in a straight line through the region ?
76. When do magnetic lines of force become. anti-clockwise ?
77. Whether electric current generates magnetic field ?
78. Who discovered the magnetic effect near the current carrying conductor ?
79. Why does the picture on a TV screen become distorted when a magnet is brought near the screen?
80. Why is an ammeter connected in series with the circuit components ?
81. Why is B non – zero outside a solenoid?
82. Why is the magnetic field due to the current flowing through a solenoid similar to a magnetic field due to a bar magnet?
83. Why is the magnetic field strength greater inside a current- carrying loop of wire?
84. Why most an ammeter be always connected in series?
85. Why should the resistance of a good voltmeter be so high that almost no current flows through it?
86. Why the resistance of an ammeter should be very low?
87. Why the voltmeter should have a very high resistance?

Long Questions

1. Describe the magnetic field due to current in a long straight wire.
2. Calculate the force on a current carrying conductor in a uniform magnetic field.
3. Explain magnetic flux and flux density.
4. Define Ampere’s law and apply it to calculate the magnetic induction inside a long solenoid having steady current I through its each turn.
5. Calculate the force on a moving charge in a magnetic field.
6. Describe the motion of charged particle in an electric and magnetic field.
7. Define Lorentz force. Discuss the determination of e/m of an electron.
8. Describe cathode ray oscilloscope in detail. What are the uses of CRO?
9. Calculate the torque on a current carrying coil.
10. Define galvanometer. Also describe principle, construction and working of a galvanometer.
11. What is the lamp and scale arrangement of a galvanometer?
12. What is the sensitivity of a galvanometer?
13. How to convert a galvanometer into an ammeter?
14. How to convert a galvanometer into a voltmeter?
15. Define ohmmeter. How to find the resistance with ohm meter?
16. Describe AVO meter multimeter.
17. Find the value of the magnetic field that will cause a maximum force of 7 x 10⁻³ N on a 20cm straight wire carrying current of 10 A.
18. How fast must a proton move in a magnetic field 2.5 x 10⁻³ T such that the magnetic force is equal to its weight?
19. A velocity selector has a magnetic field of 0.3T. If a perpendicular electric field of 10000V/m is applied, what will be the speed pf the particle that will pass through the selector?
20. A coil of 0.1m x 0.1m and of 200 turns carrying a current of 1 mA is placed in a uniform magnetic field of 0.1T. Calculate the maximum torque that acts on the coil.
21. A power line 10m high carries a current 200A. Find the magnetic field of the wire at the ground.
22. You are asked to design a solenoid that will give a magnetic field of 0.1 T, yet the current must not exceed 10 A. Find the number of turns per unit length that the solenoid should have.
23. What current should pass through a solenoid that is 0.5m long with 10000 turns of copper wire so that it will have a magnetic field of 0.4T.
24. A galvanometer having an internal resistance Rg = 15 ohm gives full scale deflection with current Ig = 10 mA. It is to be converted into an ammeter of range 10 A. Find the value of shunt resistance Rs?
25. The resistance of galvanometer is 50 ohm and reads full-scale deflection with a current of 2mA. Shown by a diagram on book how to convert this galvanometer into a voltmeter reading 200V full scale.
26. The resistance of galvanometer coil is 10 ohm and reads full scale with a current of 1 mA. What should be the values of resistance R1, r², and r³ to convert this galvanometer into a multi-range ammeter of 100, 10, and 1A

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