Explore topic-wise MCQs in Engineering.

This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.

7751.

The probability of recombination of electrons and holes in a semiconductor is proportional to

A. density of electrons
B. density of holes
C. density of electrons and holes
D. none of the above
Answer» D. none of the above
Discussion
7752.

The emf of a Weston cell is 1.286 V.

A. True
B. False
Answer» C.
Discussion
7753.

A megger has a hand driven dc generator.

A. True
B. False
Answer» B. False
Discussion
7754.

A 3-digit voltmeter having a resolution of 100 mV can be used to measure a maximum of

A. 100 V
B. 200 V
C. 1000 V
D. 5000 V
Answer» B. 200 V
Discussion
7755.

Which of the following can be used for measuring capacitance?

A. De sauty bridge
B. Maxwell's bridge
C. Anderson bridge
D. Hay's bridge
Answer» B. Maxwell's bridge
Discussion
7756.

Assertion (A): Absolute instruments are used in standard laboratories.Reason (R): Absolute instruments do not require calibration.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true
Answer» C. A is true R is false
Discussion
7757.

In indicating instruments the controlling torque is provided by a spring.

A. True
B. False
Answer» B. False
Discussion
7758.

The gauge factor of a semiconductor strain gauge is about

A. 2
B. 10
C. 100
D. 1000
Answer» D. 1000
Discussion
7759.

The damping ratio, in D'Arsonval galvanometer is equal to

A. <img src="/_files/images/electronics-and-communication-engineering/measurements-and-instrumentation/232-68-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/measurements-and-instrumentation/232-68-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/measurements-and-instrumentation/232-68-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/measurements-and-instrumentation/232-68-4.png">
Answer» C. <img src="/_files/images/electronics-and-communication-engineering/measurements-and-instrumentation/232-68-3.png">
Discussion
7760.

The pressure coil of a wattmeter should be connected to the supply side of the current coil when

A. load impedance in high
B. load impedance is low
C. voltage is high
D. voltage is low
Answer» B. load impedance is low
Discussion
7761.

Induction wattmeter is an absolute instrument.

A. True
B. False
Answer» C.
Discussion
7762.

Assertion (A): The speed of a shaft can be measured by using a dc tacho generator.Reason (R): A two phase servometer can also be used as a speed transducer.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true R is false
D. A is false R is true
Answer» C. A is true R is false
Discussion
7763.

The circuit of figure is used to measure the value Rx. Ammeter resistance Ra = 0.1 &amp;ohm; voltmeter resistance Rv = 5000 &amp;ohm;. It Rx1 and Rx2, are the measured values of Rx with switch in position 1 and 2, the mean of Rx1, and Rx2, is

A. 9.98 &ohm;
B. 10 &ohm;
C. 10.04 &ohm;
D. 10.1 &ohm;
Answer» D. 10.1 &ohm;
Discussion
7764.

Crompton potentiometer has

A. 14 coils and a slide wire all having the same resistance
B. 14 coils and a slide wire but the resistance of slide wire is half that of each coil
C. 14 coils each of different resistance
D. 14 coils out of which 7 coils have resistance which is twice that of remaining 7 coils
Answer» B. 14 coils and a slide wire but the resistance of slide wire is half that of each coil
Discussion
7765.

The flow rate of electrically conducting liquid without any suspended particle can not be measured by

A. turbine flow meter
B. electromagnetic flow meter
C. ultrasonic flow meter
D. thermistor based heat flow meter
Answer» E.
Discussion
7766.

In 3 phase power measurement by two wattmeter method, both wattmeters had equal reading. The power factor of load is

A. 1
B. 0.5 lagging
C. 0.5 leading
D. 0
Answer» B. 0.5 lagging
Discussion
7767.

Which statement out of the following statement is wrong?

A. Attenuation of satellite signals by rain and fog varies almost inversely with the angle of elevation
B. At 12/4, GHz link frequencies, signal power loss due to rain and fog is much greater than at 4/6 GHz frequencies
C. The distance between satellite and Earth station varies slightly with angle of elevation
D. At present 4/6 GHz geostationary satellites are being parked in geosynchronous, orbits at least 10 apart
Answer» E.
Discussion
7768.

The life time of a geosynchronous communication

A. 5
B. 10
C. 20
D. 50
Answer» C. 20
Discussion
7769.

The traffic-handling capacity of an Earth station on the uplink depends on

A. its EIRP
B. satellite antenna gain
C. noise associated with the satellite
D. all of the above
Answer» E.
Discussion
7770.

A microwave connector should have high SWR.

A. True
B. False
Answer» C.
Discussion
7771.

Assertion (A): Bolometer is frequently used in microwave power measurement.Reason (R): In a bolometer the input microwave power causes a change in resistance.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» C. A is correct but R is wrong
Discussion
7772.

Assertion (A): A small section of high impedance line is equivalent to a series inductance.Reason (R): A small section of a low impedance line is equivalent to a series resistance.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» D. A is wrong but R is correct
Discussion
7773.

Consider the following statements about instrument landing system of aircraft It ensures correct landing under conditions of low visibility.It consists of runaway localizer, glide path equipment and marker beacons.It is basically a blind landing system. Which of above statements are correct?

A. All
B. 1 and 2 only
C. 1 and 3 only
D. 2 only
Answer» B. 1 and 2 only
Discussion
7774.

As compared to dimensions of most feeds, the skin depth at microwave frequencies is

A. of the same magnitude
B. much larger
C. much smaller
D. either (b) or (c)
Answer» B. much larger
Discussion
7775.

In microwave communication links the fading due to rain occurs. The methods to solve this problem include

A. antenna replacement and feed correction
B. amplitude trimming and phase correction
C. polarization shifting and code diversity
D. path diversity and frequency diversity
Answer» E.
Discussion
7776.

Radar is essentially an echo ranging system

A. True
B. False
Answer» B. False
Discussion
7777.

If the peak transmitted power in a radar is increased by a factor 81, the maximum range is increased by a factor of

A. 3
B. 9
C. 27
D. 81
Answer» B. 9
Discussion
7778.

In Gunn diode electrons are transferred from

A. Ridge guide is essentially a form of capacitively loaded guide
B. low to high mobility energy bands
C. valley to domain formation
D. domain to valley formation
Answer» B. low to high mobility energy bands
Discussion
7779.

Consider the following statements about radar Beacon It is also called transponder.It includes pulse transmitter, receiver and antenna.It replies with full power even when the signal receives is weak. Which of the above statements are correct?

A. All
B. 1 and 2 only
C. 2 and 3 only
D. 2 only
Answer» B. 1 and 2 only
Discussion
7780.

Oscillations are obtained from a reflex klystron only for combinations of anode voltage and repeller voltage that give a favourable transit time.

A. True
B. False
Answer» B. False
Discussion
7781.

In the given figure shows a 10dB directional coupler. If power input at port 1 is 100 mW, power output at port 3 is

A. 10 mW
B. 15 mW
C. 20 mW
D. 25 mW
Answer» B. 15 mW
Discussion
7782.

The noise figure of klystron amplifier is about

A. 25 dB
B. 3 dB
C. zero
D. 1 dB
Answer» B. 3 dB
Discussion
7783.

In the given figure the line voltage after a number of reflections will be

A. 30 V
B. -30 V
C. 10 V
D. -10 V
Answer» D. -10 V
Discussion
7784.

When duct propagation exists

A. the line of sight and diffraction. Zone concepts are payable
B. the line of sight and diffraction zone concepts are not applicable
C. line of sight concept is applicable but diffraction zone concept is applicable
D. diffraction zone concept is not applicable but line of sight concept is not applicable
Answer» C. line of sight concept is applicable but diffraction zone concept is applicable
Discussion
7785.

For l &lt;&lt; , the equivalent circuit of a microwave resistor is

A. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-223-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-223-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-223-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-223-4.png">
Answer» C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/19-223-3.png">
Discussion
7786.

In which of the following devices can the operation be visualised in terms of a series feedback loops?

A. TWT
B. Reflex klystron
C. Klystron amplifier
D. Backward wave oscillator
Answer» E.
Discussion
7787.

The first and second subscripts in models of circular waveguides depict

A. the number of full sine wave variations in circumference in direction and Bessel function variations in radial direction respectively
B. the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively
C. the Bessel function variations in circumference direction and number of full sine wave variations in radial direction respectively
D. none of the above
Answer» B. the Bessel function variations in radial direction and the number of full sine wave variations in circumference direction respectively
Discussion
7788.

If r is relative permeability, r is relative permittivity, c is velocity of light fc is cutoff frequency, phase velocity vp (i.e., speed with which a particular phase of the wave travels down a rectangular waveguide at frequency f) is given by

A. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/12-95-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/12-95-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/12-95-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/12-95-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/12-95-2.png">
Discussion
7789.

For a directional coupler the power is in the ratio of

A. 40 dB
B. 30 dB
C. 20 dB
D. 10 dB
Answer» D. 10 dB
Discussion
7790.

The usable bandwidth of ridge wave guide

A. is lower than that of rectangular waveguide
B. is higher than that of rectangular waveguide
C. is almost same as that of rectangular waveguide
D. is very small as compared to that of rectangular waveguide
Answer» C. is almost same as that of rectangular waveguide
Discussion
7791.

As regards rectangular and circular waveguides

A. both have infinite set of TE and TM modes
B. rectangular waveguide has infinite TE and TM modes but not the circular waveguide
C. circular waveguide has infinite TE and TM modes but not the rectangular waveguide
D. none of the above
Answer» B. rectangular waveguide has infinite TE and TM modes but not the circular waveguide
Discussion
7792.

In a high frequency coaxial line and the length of line characteristic impedance is a function of

A. properties of insulating material only
B. inner and outer conductor radius only
C. both (a) and (b)
D. neither (a) nor (b)
Answer» D. neither (a) nor (b)
Discussion
7793.

Assertion (A): In TE10 mode the cutoff frequency of rectangular waveguide is where a is the broad dimension and c is velocity of light.Reason (R): TE10 mode is the dominant mode in rectangular waveguide.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» C. A is correct but R is wrong
Discussion
7794.

Characteristic impedance of a coaxial cable is inversely proportional to r.

A. True
B. False
Answer» B. False
Discussion
7795.

As compared to their values in free space

A. velocity of electric wave in dielectric is smaller but wave length of electric wave is more
B. both velocity and wave length of electric wave in dielectric are higher
C. both velocity and wave length of electric wave in dielectric are smaller
D. wave length of electric wave is less but velocity is more in dielectric
Answer» D. wave length of electric wave is less but velocity is more in dielectric
Discussion
7796.

A 3 port circulator is in the given figure. Its scattering matrix is

A. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/16-174-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/16-174-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/16-174-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/16-174-4.png">
Answer» B. <img src="/_files/images/electronics-and-communication-engineering/microwave-communication/16-174-2.png">
Discussion
7797.

The total power radiated from an antenna system is determined by imagining that the antenna is at the centre of a very large

A. sphere
B. rectangle
C. square
D. ellipse
Answer» B. rectangle
Discussion
7798.

Assertion (A): In TE mode for rectangular waveguide.Reason (R): In TM mode for rectangular waveguide.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is correct but R is wrong
D. A is wrong but R is correct
Answer» C. A is correct but R is wrong
Discussion
7799.

The AM, PM, and TV broadcast frequencies are

A. of the same order as microwave range
B. much lower than microwave range
C. much higher than microwave range
D. either (a) or (c)
Answer» C. much higher than microwave range
Discussion
7800.

A rectangular waveguide has a discontinuity in the form of reduced narrow dimension. In the equivalent circuit this discontinuity can be represented by

A. a shunt capacitance at the discontinuity
B. a shunt inductance at the discontinuity
C. a shunt resistance at the discontinuity
D. none of the above
Answer» B. a shunt inductance at the discontinuity
Discussion