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1 A metal rod of 25 cm length is moving at a speed of 0.5/sec in direction perpendicular to 0.25T magnetic field. Emf produced in the rod is

A 0 volt B 3.125 volt C 31.25 volt D 0.03125 volt

✅ Correct Answer: 4

2 The emf induced in a coil by a changing magnetic flux may have unit as

A ms-1A B ms-2A-1 C kgms2A-1 D kgm2s-1A-1

✅ Correct Answer: 4

3 A coil of wire is arranged with its plan perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time ?t then what is the emf induced in the coil?

A ?B/r22-r12/?t B ?B(r2-r1)2/?t C ?B(r22-r12)/?t D ?B(r22+r12)/?t

✅ Correct Answer: 3

4 The emf induced in a conductor of unit length moving with unit velocity at right angles to a magnetic field is equal to

A Magnetic flux density B Torque C Mutual induction D Motional emf

✅ Correct Answer: 1

5 The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core

A Decreases the resistance of the solenoid B Reduces the effect of eddy current C Improves the flux linkage between the turns of the coil D Increases the mutual inductance between the solenoid and the core

✅ Correct Answer: 3

6 A small coil lies inside a large coil. The two coils are horizontal concentric and carry currents in opposite directions. The large coil will experience

A A torque about horizontal axis B A torque about vertical axis C An upward force along the axis D No resultant force

✅ Correct Answer: 4

7 An aeroplane of wingspan 10m flies from the equator towards the North Pole. The wings are perpendicular to the vertical component of the earths magnetic field (B = 4x10-5T). At maximum speed an emf of 96mV is induced across the wing tips. The maximum speed of the aeroplane is

A 150msec-1 B 384msec-1 C 38.4msec-1 D 200msec-1

✅ Correct Answer: 2

8 A.C can not be used for

A producing heat B producing light C Magnetizing iron D Producing magnetic field

✅ Correct Answer: 3

9 Non inductive resistances are used in decreasing

A Mutual inductance B Self inductance C Magnetic fields D Heating effect

✅ Correct Answer: 2

10 Magnetic compass needle will be deflecting if it is kept near

A Static charge B Soft iron C Semi-conductor D Accelerating charge

✅ Correct Answer: 4

11 The alternating current has frequency of 106 Hz in such a way that time period for completion of cycle is

A 1?s B 1.5?s C 106sec D 1sec

✅ Correct Answer: 1

12 Long distance transmission is easy for

A D.C voltage B A.C voltage C Half A.C voltage D Half D.C voltage

✅ Correct Answer: 2

13 Which one of the following devices does not function like an electric motor?

A Galvanometer B Ammeter C Voltmeter D Transformer

✅ Correct Answer: 4

14 The out put voltage of a transformer is 3 times the input voltage then turns ratio will be

A 03-Jan B 3 C 1 D 6

✅ Correct Answer: 2

15 For long distance transmission the transformer used is

A Step down B Input voltage and output voltage remain same C Step up D Amplifier is used

✅ Correct Answer: 3

16 Self inductance of a long solenoid is

A ??n2?A B ??n2A/? C ??N2?A D BA

✅ Correct Answer: 1

17 An electric current induced within the body of a conductor when that conductor either moves through a non uniform magnetic field or in a region where there is a change in magnetic flux is called

A Induced current B Eddy current C Back emf D None of the above

✅ Correct Answer: 2

18 Lagging of changes in the magnetization of a substance behind changes in the magnetic field as the magnetic field is varied is known as magnetic

A Retaintivity B Permeability C Flux D Hysteresis

✅ Correct Answer: 4

19 Transformer works on the principle of

A Lenzs law B Faradays law C Mutual induction D Law of conservation of power

✅ Correct Answer: 3

20 When the motor is at its maximum speed then back emf will be

A Maximum B Zero C Intermediate values D No back emf

✅ Correct Answer: 1

21 Electrons present in p-type material due to thermal pair generation are

A majority carriers B minority carriers C dual carriers D blockers

✅ Correct Answer: 2

22 Semi-conductors with donor atoms and free electrons belong to the type

A n B p C mix D any of above

✅ Correct Answer: 1

23 Semi-conductor germanium and silicon are

A pentavalent B trivalent C divalent D tetravalent

✅ Correct Answer: 4

24 Acceptor and donor impurities donate

A n-carriers only B p-carriers only C p-carriers and n-carriers respectively D n-carriers and p-carriers respectively

✅ Correct Answer: 3

25 p-n junction when reversed biased acts as a

A capacitor B inductor C on switch D off switch

✅ Correct Answer: 4

26 In p-n-p transistor the collector current is

A equal to emitter current B slightly less than emitter current C greater than emitter current D any of above

✅ Correct Answer: 2

27 In n-p-n transistor, p works as

A collector B emitter C base D any of above

✅ Correct Answer: 3

28 The simplest type of rectification known as half wave rectification is obtained by

A using a transistor B suppressing the harmonics in A.C voltage C suppressing half wave of A.C supply by using diode D using a Coolidge tube

✅ Correct Answer: 3

29 Identify the correct statement about minority carriers

A holes in n-type and free electrons in p-type B holes in n-type and p-type C free electrons in n-type and holes in p-type D free electrons in n-type and p-type

✅ Correct Answer: 1

30 Depletion region of a junction is formed

A during the manufacturing process B under forward bias C under reverse bias D when temperature varies

✅ Correct Answer: 1

31 The velocity of an oscillating charge as it moves to and fro along a wire is always

A constant B zero C changing D infinite

✅ Correct Answer: 3

32 Which one of following band is completely filled in case of conductors?

A Conduction band B Fermi band C Valence band D Forbidden band

✅ Correct Answer: 1

33 Which one of the following has the greatest energy gap?

A insulator B conductor C semi conductor D any of above

✅ Correct Answer: 1

34 The value of resistivity for insulator is of the order of

A 105 ohm metre B 106 ohm metre C 107 ohm metre D 108 ohm metre

✅ Correct Answer: 4

35 Thermions are

A protons B positrons C electrons D photons

✅ Correct Answer: 3

36 Hole is equivalent to

A a negative charge B a positive charge C a neutral particle D an electron

✅ Correct Answer: 2

37 Which one of the following is not a donor impurity?

A antimony B phosphorus C aluminium D arsenic

✅ Correct Answer: 3

38 Forward current through a semi conductor diode circuit is due to

A minority carriers B majority carriers C holes D electrons

✅ Correct Answer: 2

39 In the transistor schematic symbol, the arrow

A is located on the emitter B is located on the base C is locate on the collector D points form north to south

✅ Correct Answer: 1

40 In full wave rectification the output D.C. voltage across the load is obtained for

A The positive half cycle of input A.C. B The negative half cycle of input A.C. C The complete cycle of input A.C. D All of the above.

✅ Correct Answer: 3

41 The semiconductor diode can be used as a rectifier because _

A It has low resistance to the current flow when forward biased & high resistance when reverse biased. B It has low resistance to the current flow when forward biased. C It has high resistance to the current flow when reverse biased D Its conductivity increases with rise of temperature.

✅ Correct Answer: 1

42 In half-wave rectification the output D.C. voltages is obtained across the load for

A The negative half cycle of A.C. B The positive half cycle of A.C. C The positive and negative half cycles D Either positive or negative half of A.C.

✅ Correct Answer: 2

43 The device or circuit used for conversion of A.C. into D.C. is called

A An amplifier. B A rectifier C Filtering circuit D Converter.

✅ Correct Answer: 2

44 The device used for conversion of D.C. to A.C. is called

A Converter B A rectifier C Inverter D Oscillator

✅ Correct Answer: 4

45 The especially designed semiconductor diodes used as indicator lamps in electronic circuits are

A The switch B The light emitting diode C The photo diodes D Solar cells.

✅ Correct Answer: 2

46 The specially designed semi-conductor diodes used as fast counters in electronic circuits are

A The light emitting diodes B Photo diodes C Photo voltaic cell D Solar cells.

✅ Correct Answer: 2

47 The alternating voltage is an example of

A A digital waveform B An analogue waveform C Discrete waveform D None at all

✅ Correct Answer: 2

48 The rectangular voltage is an example of

A An analogue waveform B Continuous wave form C Electronic waveform D A digital waveform

✅ Correct Answer: 4

49 The operational amplifier is

A A high gain amplifier B A high-power amplifier C A high resistance amplifier D A low resistance amplifier

✅ Correct Answer: 1

50 In a half-wave rectifier the r.m.s. value of the A.C. component of the wave is

A Equal to D.C. value B More than D.C. value C Less than D.C. value D Zero

✅ Correct Answer: 2

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