MCAT MCQ Quiz Hub

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
0 volt
3.125 volt
31.25 volt
0.03125 volt

2. The emf induced in a coil by a changing magnetic flux may have unit as
ms-1A
ms-2A-1
kgms2A-1
kgm2s-1A-1

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

4. The emf induced in a conductor of unit length moving with unit velocity at right angles to a magnetic field is equal to
Magnetic flux density
Torque
Mutual induction
Motional emf

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

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

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
150msec-1
384msec-1
38.4msec-1
200msec-1

8. A.C can not be used for
producing heat
producing light
Magnetizing iron
Producing magnetic field

9. Non inductive resistances are used in decreasing
Mutual inductance
Self inductance
Magnetic fields
Heating effect

10. Magnetic compass needle will be deflecting if it is kept near
Static charge
Soft iron
Semi-conductor
Accelerating charge

11. The alternating current has frequency of 106 Hz in such a way that time period for completion of cycle is
1?s
1.5?s
106sec
1sec

12. Long distance transmission is easy for
D.C voltage
A.C voltage
Half A.C voltage
Half D.C voltage

13. Which one of the following devices does not function like an electric motor?
Galvanometer
Ammeter
Voltmeter
Transformer

14. The out put voltage of a transformer is 3 times the input voltage then turns ratio will be
03-Jan
3
1
6

15. For long distance transmission the transformer used is
Step down
Input voltage and output voltage remain same
Step up
Amplifier is used

16. Self inductance of a long solenoid is
??n2?A
??n2A/?
??N2?A
BA

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
Induced current
Eddy current
Back emf
None of the above

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
Retaintivity
Permeability
Flux
Hysteresis

19. Transformer works on the principle of
Lenzs law
Faradays law
Mutual induction
Law of conservation of power

20. When the motor is at its maximum speed then back emf will be
Maximum
Zero
Intermediate values
No back emf

21. Electrons present in p-type material due to thermal pair generation are
majority carriers
minority carriers
dual carriers
blockers

22. Semi-conductors with donor atoms and free electrons belong to the type
n
p
mix
any of above

23. Semi-conductor germanium and silicon are
pentavalent
trivalent
divalent
tetravalent

24. Acceptor and donor impurities donate
n-carriers only
p-carriers only
p-carriers and n-carriers respectively
n-carriers and p-carriers respectively

25. p-n junction when reversed biased acts as a
capacitor
inductor
on switch
off switch

26. In p-n-p transistor the collector current is
equal to emitter current
slightly less than emitter current
greater than emitter current
any of above

27. In n-p-n transistor, p works as
collector
emitter
base
any of above

28. The simplest type of rectification known as half wave rectification is obtained by
using a transistor
suppressing the harmonics in A.C voltage
suppressing half wave of A.C supply by using diode
using a Coolidge tube

29. Identify the correct statement about minority carriers
holes in n-type and free electrons in p-type
holes in n-type and p-type
free electrons in n-type and holes in p-type
free electrons in n-type and p-type

30. Depletion region of a junction is formed
during the manufacturing process
under forward bias
under reverse bias
when temperature varies

31. The velocity of an oscillating charge as it moves to and fro along a wire is always
constant
zero
changing
infinite

32. Which one of following band is completely filled in case of conductors?
Conduction band
Fermi band
Valence band
Forbidden band

33. Which one of the following has the greatest energy gap?
insulator
conductor
semi conductor
any of above

34. The value of resistivity for insulator is of the order of
105 ohm metre
106 ohm metre
107 ohm metre
108 ohm metre

35. Thermions are
protons
positrons
electrons
photons

36. Hole is equivalent to
a negative charge
a positive charge
a neutral particle
an electron

37. Which one of the following is not a donor impurity?
antimony
phosphorus
aluminium
arsenic

38. Forward current through a semi conductor diode circuit is due to
minority carriers
majority carriers
holes
electrons

39. In the transistor schematic symbol, the arrow
is located on the emitter
is located on the base
is locate on the collector
points form north to south

40. In full wave rectification the output D.C. voltage across the load is obtained for
The positive half cycle of input A.C.
The negative half cycle of input A.C.
The complete cycle of input A.C.
All of the above.

41. The semiconductor diode can be used as a rectifier because _
It has low resistance to the current flow when forward biased & high resistance when reverse biased.
It has low resistance to the current flow when forward biased.
It has high resistance to the current flow when reverse biased
Its conductivity increases with rise of temperature.

42. In half-wave rectification the output D.C. voltages is obtained across the load for
The negative half cycle of A.C.
The positive half cycle of A.C.
The positive and negative half cycles
Either positive or negative half of A.C.

43. The device or circuit used for conversion of A.C. into D.C. is called
An amplifier.
A rectifier
Filtering circuit
Converter.

44. The device used for conversion of D.C. to A.C. is called
Converter
A rectifier
Inverter
Oscillator

45. The especially designed semiconductor diodes used as indicator lamps in electronic circuits are
The switch
The light emitting diode
The photo diodes
Solar cells.

46. The specially designed semi-conductor diodes used as fast counters in electronic circuits are
The light emitting diodes
Photo diodes
Photo voltaic cell
Solar cells.

47. The alternating voltage is an example of
A digital waveform
An analogue waveform
Discrete waveform
None at all

48. The rectangular voltage is an example of
An analogue waveform
Continuous wave form
Electronic waveform
A digital waveform

49. The operational amplifier is
A high gain amplifier
A high-power amplifier
A high resistance amplifier
A low resistance amplifier

50. In a half-wave rectifier the r.m.s. value of the A.C. component of the wave is
Equal to D.C. value
More than D.C. value
Less than D.C. value
Zero