R4RIN – MCQs, Mock Tests | MCAT MCAT Physics Mcq Questions Electronics

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

1. 0 volt
2. 3.125 volt
3. 31.25 volt
4. 0.03125 volt

✅ Correct Answer: 4

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

1. ms-1A
2. ms-2A-1
3. kgms2A-1
4. kgm2s-1A-1

✅ Correct Answer: 4

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?

1. ?B/r22-r12/?t
2. ?B(r2-r1)2/?t
3. ?B(r22-r12)/?t
4. ?B(r22+r12)/?t

✅ Correct Answer: 3

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

1. Magnetic flux density
2. Torque
3. Mutual induction
4. Motional emf

✅ Correct Answer: 1

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

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

✅ Correct Answer: 3

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

1. A torque about horizontal axis
2. A torque about vertical axis
3. An upward force along the axis
4. No resultant force

✅ Correct Answer: 4

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

1. 150msec-1
2. 384msec-1
3. 38.4msec-1
4. 200msec-1

✅ Correct Answer: 2

A.C can not be used for

1. producing heat
2. producing light
3. Magnetizing iron
4. Producing magnetic field

✅ Correct Answer: 3

Non inductive resistances are used in decreasing

1. Mutual inductance
2. Self inductance
3. Magnetic fields
4. Heating effect

✅ Correct Answer: 2

Magnetic compass needle will be deflecting if it is kept near

1. Static charge
2. Soft iron
3. Semi-conductor
4. Accelerating charge

✅ Correct Answer: 4

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

1. 1?s
2. 1.5?s
3. 106sec
4. 1sec

✅ Correct Answer: 1

Long distance transmission is easy for

1. D.C voltage
2. A.C voltage
3. Half A.C voltage
4. Half D.C voltage

✅ Correct Answer: 2

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

1. Galvanometer
2. Ammeter
3. Voltmeter
4. Transformer

✅ Correct Answer: 4

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

1. 03-Jan
2. 3
3. 1
4. 6

✅ Correct Answer: 2

For long distance transmission the transformer used is

1. Step down
2. Input voltage and output voltage remain same
3. Step up
4. Amplifier is used

✅ Correct Answer: 3

Self inductance of a long solenoid is

1. ??n2?A
2. ??n2A/?
3. ??N2?A
4. BA

✅ Correct Answer: 1

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

1. Induced current
2. Eddy current
3. Back emf
4. None of the above

✅ Correct Answer: 2

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

1. Retaintivity
2. Permeability
3. Flux
4. Hysteresis

✅ Correct Answer: 4

Transformer works on the principle of

1. Lenzs law
2. Faradays law
3. Mutual induction
4. Law of conservation of power

✅ Correct Answer: 3

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

1. Maximum
2. Zero
3. Intermediate values
4. No back emf

✅ Correct Answer: 1

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

1. majority carriers
2. minority carriers
3. dual carriers
4. blockers

✅ Correct Answer: 2

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

1. n
2. p
3. mix
4. any of above

✅ Correct Answer: 1

Semi-conductor germanium and silicon are

1. pentavalent
2. trivalent
3. divalent
4. tetravalent

✅ Correct Answer: 4

Acceptor and donor impurities donate

1. n-carriers only
2. p-carriers only
3. p-carriers and n-carriers respectively
4. n-carriers and p-carriers respectively

✅ Correct Answer: 3

p-n junction when reversed biased acts as a

1. capacitor
2. inductor
3. on switch
4. off switch

✅ Correct Answer: 4

In p-n-p transistor the collector current is

1. equal to emitter current
2. slightly less than emitter current
3. greater than emitter current
4. any of above

✅ Correct Answer: 2

In n-p-n transistor, p works as

1. collector
2. emitter
3. base
4. any of above

✅ Correct Answer: 3

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

1. using a transistor
2. suppressing the harmonics in A.C voltage
3. suppressing half wave of A.C supply by using diode
4. using a Coolidge tube

✅ Correct Answer: 3

Identify the correct statement about minority carriers

1. holes in n-type and free electrons in p-type
2. holes in n-type and p-type
3. free electrons in n-type and holes in p-type
4. free electrons in n-type and p-type

✅ Correct Answer: 1

Depletion region of a junction is formed

1. during the manufacturing process
2. under forward bias
3. under reverse bias
4. when temperature varies

✅ Correct Answer: 1

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

1. constant
2. zero
3. changing
4. infinite

✅ Correct Answer: 3

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

1. Conduction band
2. Fermi band
3. Valence band
4. Forbidden band

✅ Correct Answer: 1

Which one of the following has the greatest energy gap?

1. insulator
2. conductor
3. semi conductor
4. any of above

✅ Correct Answer: 1

The value of resistivity for insulator is of the order of

1. 105 ohm metre
2. 106 ohm metre
3. 107 ohm metre
4. 108 ohm metre

✅ Correct Answer: 4

Thermions are

1. protons
2. positrons
3. electrons
4. photons

✅ Correct Answer: 3

Hole is equivalent to

1. a negative charge
2. a positive charge
3. a neutral particle
4. an electron

✅ Correct Answer: 2

Which one of the following is not a donor impurity?

1. antimony
2. phosphorus
3. aluminium
4. arsenic

✅ Correct Answer: 3

Forward current through a semi conductor diode circuit is due to

1. minority carriers
2. majority carriers
3. holes
4. electrons

✅ Correct Answer: 2

In the transistor schematic symbol, the arrow

1. is located on the emitter
2. is located on the base
3. is locate on the collector
4. points form north to south

✅ Correct Answer: 1

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

1. The positive half cycle of input A.C.
2. The negative half cycle of input A.C.
3. The complete cycle of input A.C.
4. All of the above.

✅ Correct Answer: 3

The semiconductor diode can be used as a rectifier because _

1. It has low resistance to the current flow when forward biased & high resistance when reverse biased.
2. It has low resistance to the current flow when forward biased.
3. It has high resistance to the current flow when reverse biased
4. Its conductivity increases with rise of temperature.

✅ Correct Answer: 1

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

1. The negative half cycle of A.C.
2. The positive half cycle of A.C.
3. The positive and negative half cycles
4. Either positive or negative half of A.C.

✅ Correct Answer: 2

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

1. An amplifier.
2. A rectifier
3. Filtering circuit
4. Converter.

✅ Correct Answer: 2

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

1. Converter
2. A rectifier
3. Inverter
4. Oscillator

✅ Correct Answer: 4

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

1. The switch
2. The light emitting diode
3. The photo diodes
4. Solar cells.

✅ Correct Answer: 2

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

1. The light emitting diodes
2. Photo diodes
3. Photo voltaic cell
4. Solar cells.

✅ Correct Answer: 2

The alternating voltage is an example of

1. A digital waveform
2. An analogue waveform
3. Discrete waveform
4. None at all

✅ Correct Answer: 2

The rectangular voltage is an example of

1. An analogue waveform
2. Continuous wave form
3. Electronic waveform
4. A digital waveform

✅ Correct Answer: 4

The operational amplifier is

1. A high gain amplifier
2. A high-power amplifier
3. A high resistance amplifier
4. A low resistance amplifier

✅ Correct Answer: 1

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

1. Equal to D.C. value
2. More than D.C. value
3. Less than D.C. value
4. Zero

✅ Correct Answer: 2