Practice MCQ

Q1: Which of the following does not change in a transformer?

A. Current
B. Voltage
C. Frequency
D. all of these

Q2: A transformer core is laminated to

A. reduce hysteresis loss
B. reduce eddy current losses
C. reduce copper losses
D. none of these

Q3: A certain oscillator has a tap on the inductor in the tank circuit.This oscillator is probably

A. a Colpitts Oscillator
B. a Crystal oscillator
C. a Hartely oscillator
D. a Clap Oscillator

Q4: For a forward bias diode the barrier potential _____ as temperature increases

A. decreases
B. increases
C. remains constant
D. can't say

Q5: Reverse break down isa condition in which a diode

A. is subjected to a large reverse voltage
B. is reversed bias and there is small leakage in current
C. has no current flowing at all
D. heated up bylarge amount of current

Q6: Signals with a frequency above 30Mhz use _________ propagation

A. Sky wave
B. line of sight
C. Ground wave
D. none of these

Q7: A 50Ω trasmission line that has impedance load of 300Ω has a VSWR

A. 06:01
B. 01:06
C. 05:07
D. 07:05

Q8: The input impedance at the center ofa dipole antenna is approximately

A. 50Ω
B. 73Ω
C. 100Ω
D. 80Ω

Q9: The characeteristic impedance of free space is ___ ohms

A. not known
B. infinity
C. 50Ω
D. 377Ω

Q10: A zener diode has

A. high forward voltage rating
B. sharp breakdown at low reverse voltage
C. a negative resistance
D. none of the above

Q11: Negative feedback in an amplifier

A. reduces the voltage gain
B. increases the voltage gain
C. converts the amplifier in to an oscillator
D. does not affect the voltage gain

Q12: A series of RL flter circuit with an output across the inductor will result in what type of filtering

A. passing of the higher frequencies
B. passing of the lower frequencies
C. blocking of the higher frequencies
D. blocking of the lower frequencies

Q13: The DC current through each diode in a bridge rectifier equals

A. the load current
B. half the DC load current
C. twice the Dc load current
D. one fourth of the Dcload current

Q14: The oscillator that makes a communication receiver capable of receiving Morse codeis

A. Voltage controlled oscillator
B. local oscillator
C. Beat frequency oscillator
D. Phase locked loop

Q15: A receiver has poor IF selectivity. I will therefore also have poor

A. blocking
B. double spotting
C. diversity reception
D. senstivity

Q16: Higher Q of a series circuit

A. has greater band width
B. sharper its resonance curve
C. boader its resonance curve
D. narrower its pass band

Q17: When a transistor is used as switch its ON/OFF terminals are

A. collector to emitter
B. collector to base
C. emitter to base
D. through B/E junction

Q18: For a satellite communication the frequency should be

A. equal to the critical frequency
B. less than the critical frequency
C. more than the critical frequency
D. none

Q19: When modulation of AM wave is decreased

A. the percentage carrier power is decreased
B. the percentage of carrier power is increased
C. total tranmitted pwer is increased
D. percentage side band power is unaffected

Q20: The beakdown mechanism in a lightly doped p-n junction under reversebiased contion is called

A. avalanche breakdown
B. zener breakdown
C. breakdown by tunnelling
D. high voltage breakdown

Q21: Ohm's law not applicable to

A. copper
B. silver
C. aliminium
D. silicon carbide

Q22: In a pure capacitor the phase relation between the current and voltage is

A. current lags the voltageby 90 degrees
B. current leads the voltage by 90 degrees
C. both are phase
D. none of the above

Q23: The right most band in a resisitor indicates

A. power rating
B. tolerance
C. dissipating capacity
D. moltiplicity

Q24: A resonant frequency total impedance of series RLC circuit depends on

A. R only
B. L &C
C. R l & C
D. inpedance is Zero atresonant

Q25: Which class of amplifier to pickup and reproduce weak radio signal is

A. Selectivity
B. Sensitivity
C. Detection
D. tracking ablity

Q26: Which block of the super hetrodyne receiver is known as first detector

A. RF amplifier
B. Mixer circuit
C. IF amplifier
D. Antenna

Q27: Which of the following block is not present in tuned radio frequency

A. RF amplifier
B. Detector
C. IF amplifier
D. AF amplifier

Q28: The range of carrier frquencies identified for amplitude modulation transmission falls in ____ band

A. HF
B. VHF
C. MF
D. LF

Q29: For a signal band limited to W Hz thebandwidth of its SSB modulated signal is

A. W Hz
B. 2W Hz
C. W/2 Hz
D. W/4

Q30: For a class B amplifier theQpoint is

A. at the scenter of the load line
B. exatly at thecut off
C. beyond the cutt off point
D. above but close to the cut off point

Q31: In FM modulation frequency deviation is mainly depemdt on

A. carrier amplitude
B. modulating signal amplitude
C. carrier frequency
D. modulating frequency

Q32: The primary advantage of a crystal oscillator is that

A. it canoscillate at anyfrequency
B. it gives a high output voltage
C. it frquency of oscillation remains allmost constant
D. it operates on low DC voltage

Q33: The intrinsic semiconductor at the absolute zero of temparature

A. behaves like an insulator
B. has large number of electrons
C. has a large number of holes
D. behaves like a metalic conductor

Q34: For sustaining oscilations in an oscillator

A. feed back factor should be unity
B. phase shiftshould be Zero degree
C. feed back should be negative
D. both a&b

Q35: An inductor opposes

A. an increase in applied voltage
B. an increase in current flow
C. a decrease in current flow
D. both a &c

Q36: In a full wave rectifier the current in each of the diode flows for

A. the complete cycle of the input signal
B. half the cycle of the input signal
C. less than half cycle of the input signal
D. zero time

Q37: In the process of modulation in communication system

A. signa frequency is more than the carrier frequency
B. signal frequencyis less than the carrier frequency
C. signal frequency will be directly transmitted
D. signal frequency equals carrier frequency

Q38: The output signal of a detector in a communication receiver is in

A. Audio frequency range
B. Radio frequency range
C. Intermediate frequency range
D. none of the above

Q39: In a radio receiver the selectivity will be governed by

A. Detector
B. Intermediate frequency
C. Audio frequency
D. Beat frequency

Q40: The emf of a cell depends on

A. nature of elctrodes and elctrolyte
B. size of the electrodes
C. spacing between the elctrodes
D. none of the above

Q41: The mutual inductance (M) between two coils of self inductance L1 & L2 is expressed as

A. M=√L1L2
B. M=1√L1L2
C. M=k√L1L2
D. M=K√L1+L2

Q42: The SI unit of resistivity is

A. Ohm-m
B. Ohm/m
C. Mho-m
D. none

Q43: The capacitance of a capacitor is not influenced by

A. Plate thickness
B. Plate area
C. Plate separate
D. nature of the dielectric

Q44: A signal (fm) is amplitude modulated with a carrier (fc) the frequency value of lower side band is

A. fm-fc
B. fc-fm
C. fm+fc
D. none

Q45: The highest frequency that is reflected by an inosphere layer is

A. Maximum usable frequency
B. Critical frequency
C. carrier frequency
D. all of the above

Q46: Two resistors are in parallel. Resistor A carries twice the current of ResistorB implies

A. A has half the resistance of B
B. B has half the resistance of A
C. the voltage across A is twice that of across B
D. The voltage across B is twice that of across A

Q47: The SSB transmission

A. occupy about twice the bandwidth of AM transmission
B. occupy about half the the bandwidth of AM transmission
C. contains more information than Am transmission
D. are compatible with FM transmission

Q48: Selectivity in a super hetrodyne receiver is achived primarily in the

A. RF amplifier
B. IF amplifier
C. Mixer
D. audio stage

Q49: The polarizationof an electromagnatic waveis defined by the direction of

A. the H fileld
B. The E field
C. propagation
D. the receiving antenna

Q50: What is the name of a current that flows only in one direction?

A. An alternating current
B. A direct current
C. A normal current
D. A smooth current

Q51: What is the standard unit of frequency?

A. The megacycle
B. The Hertz
C. One thousand cycles per second
D. The electromagnetic force

Q52: How much voltage does an automobile battery normally supply?

A. About 12 volts
B. About 30 volts
C. About 120 volts
D. About 240 volts

Q53: Which of the following describes a linear amplifier?

A. Any RF power amplifier used in conjunction with an amateur transceiver
B. An amplifier whose output preserves the input waveform
C. A Class C high efficiency amplifier
D. An amplifier used as a frequency multiplier

Q54: How is the efficiency of an RF power amplifier determined?

A. Divide the DC input power by the DC output power
B. Divide the RF output power by the DC input power
C. Multiply the RF input power by the reciprocal of the RF output power
D. Add the RF input power to the DC output power

Q55: Which of the following is an advantage of a Class C amplifier?

A. High efficiency
B. Linear operation
C. No need for tuned circuits
D. All of these answers are correct

Q56: For which of the following modes is a Class C power stage appropriate for amplifying a modulated signal?

A. SSB
B. CW
C. AM
D. All of these answers are correct

Q57: Which of the following is a characteristic of a Class A amplifier?

A. Low standby power
B. High Efficiency
C. No need for bias
D. Low distortion

Q58: What is the output waveform of an unfiltered full-wave rectifier connected to a resistive load?

A. A series of DC pulses at twice the frequency of the AC input
B. A series of DC pulses at the same frequency as the AC input
C. A sine wave at half the frequency of the AC input
D. A steady DC voltage

Q59: What portion of the AC cycle is converted to DC by a full-wave rectifier?

A. 90 degrees
B. 180 degrees
C. 270 degrees
D. 360 degrees

Q60: What portion of the AC cycle is converted to DC by a half-wave rectifier?

A. 90 degrees
B. 180 degrees
C. 270 degrees
D. 360 degrees

Q61: What type of circuit is used in many FM receivers to convert signals coming from the IF amplifier to audio?

A. Product detector
B. Phase inverter
C. Mixer
D. Discriminator

Q62: What type of receiver is suitable for CW and SSB reception but does not require a mixer stage or an IF amplifier?

A. A super-regenerative receiver
B. A TRF receiver
C. A super-heterodyne receiver
D. A direct conversion receiver

Q63: What is an advantage of a crystal controlled transmitter?

A. Stable output frequency
B. Excellent modulation clarity
C. Ease of switching between bands
D. Ease of changing frequency

Q64: A superhetrodyne receiver is tuned to 555 KHz and its local oscillator at 1010 KHz . The image frequency will be

A. 1565 KHz
B. 455 KHz
C. 1465 KHz
D. none ofthese

Q65: 3 to 30 MHz band is known as

A. LF
B. MF
C. HF
D. VHF

Q66: The wavelength of a broadcast station at 1000 KHz is

A. 30 Meters
B. 300 Meters
C. 3000Meters
D. none ofthese

Q67: The core of power supply transformer is laminated to …

A. decrease impedance
B. increase impedance
C. decrease eddy current losses
D. none of these

Q68: In a resonant circuit

A. Xl = Xc
B. Xl > Xc
C. Xl < Xc
D. none of these

Q69: When frequency of a carrier is varied according to modulation the result is

A. frequency modulation
B. amplitude modulation
C. product detection
D. none of these

Q70: what is the phase relationship between the input and output of a common emitter circuit in degrees?

A. 90
B. 180
C. 270
D. 0

Q71: The quartz crystal oscillator is known for its

A. linearity
B. stability
C. flexibility
D. high output

Q72: Which of the following is a characteristic of a liquid crystal display?

A. It requires ambient or back lighting
B. It offers a wide dynamic range
C. It has a wide viewing angle
D. All of these choices are correct

Q73: What is meant by the term MMIC?

A. Multi Megabyte Integrated Circuit
B. Military-specification Manufactured Integrated Circuit
C. Monolithic Microwave Integrated Circuit
D. Mode Modulated Integrated Circuit

Q74: What is a microprocessor?

A. A low powered analog signal processor used as a microwave detector
B. A miniature computer on a single integrated circuit chip
C. A microwave detector, amplifier, and local oscillator on a chip
D. A low voltage amplifier used in a microwave transmitter modulator stage

Q75: What safety feature does a power-supply bleeder resistor provide?

A. It acts as a fuse for excess voltage
B. It discharges the filter capacitors
C. It removes shock hazards from the induction coils
D. It eliminates ground-loop current

Question Pool: General Grade

SECTION: A: Radio Theory

Model question pool - 1