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MCQOPTIONS
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.
| 2851. |
Which of the following statement about the photo electric emission is incorrect? |
| A. | The maximum velocity of emission varies with the frequency of incident light |
| B. | The maximum velocity of emission varies with the intensity of light |
| C. | The amount of photoelectric emission is directly proportional to the intensity of light |
| D. | The quantum yield depends on the frequency and not the intensity of incident light |
| Answer» C. The amount of photoelectric emission is directly proportional to the intensity of light | |
| 2852. |
No load d.c. output will be least in case of |
| A. | half wave rectifier |
| B. | full wave rectifier |
| C. | bridge rectifier |
| D. | three phase full wave rectifier |
| Answer» B. full wave rectifier | |
| 2853. |
In a semiconductor avalanche breakdown occurs when |
| A. | reverse bias exceeds the limiting value |
| B. | forward bias exceeds the limiting value |
| C. | forward current exceeds the limiting value |
| D. | potential barrier is reduced to zero |
| Answer» B. forward bias exceeds the limiting value | |
| 2854. |
When an electron breaks a covalent bond and moves away, |
| A. | a hole is created |
| B. | a proton is also lost |
| C. | atom becomes an ion |
| D. | rest of the electron move at a faster rate |
| Answer» B. a proton is also lost | |
| 2855. |
A photo diode is |
| A. | forward biased |
| B. | reverse biased |
| C. | either forward or reverse biased |
| D. | unbiased |
| Answer» C. either forward or reverse biased | |
| 2856. |
Germanium and Si phosphorus have their maximum spectral response in the |
| A. | infrared region |
| B. | ultraviolet region |
| C. | visible region |
| D. | X-ray region |
| Answer» C. visible region | |
| 2857. |
In which condition does BJT behave like a closed switch? |
| A. | Cut off |
| B. | Saturation |
| C. | Forward active |
| D. | Reverse active |
| Answer» C. Forward active | |
| 2858. |
In fabricating silicon BJT in ICs by the epitaxial process, the number of diffusions used is usually |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 6 |
| Answer» E. | |
| 2859. |
The emission of light is LED due to |
| A. | emission of holes |
| B. | emission of electrons |
| C. | generation of electromagnetic radiations |
| D. | conversion of heat energy into illumination |
| Answer» D. conversion of heat energy into illumination | |
| 2860. |
Which of the following exhibits negative resistance in a portion of its characteristics? |
| A. | Tunnel diode |
| B. | Zener diode |
| C. | JFET |
| D. | MOSFET and tunnel diode |
| Answer» B. Zener diode | |
| 2861. |
For bipolar transistor |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/42-159-1.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/42-159-2.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/42-159-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/42-159-4.png"> |
| Answer» B. <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/42-159-2.png"> | |
| 2862. |
The sum of two or more arbitrary sinusoidal is |
| A. | always periodic |
| B. | periodic under certain conditions |
| C. | never periodic |
| D. | periodic only if all the sinusoidals are identical in frequency and phase |
| Answer» E. | |
| 2863. |
Which of the following is used as a passive component in electronic circuits? |
| A. | Tunnel diode |
| B. | Capacitor |
| C. | Transistor |
| D. | Vacuum tube |
| Answer» C. Transistor | |
| 2864. |
Barkhausen criterion of oscillation is |
| A. | A > 1 |
| B. | A = 1 |
| C. | A = < 1 |
| D. | A 1 |
| Answer» C. A = < 1 | |
| 2865. |
Eg is the band gap, A is pre-factor, k is Boltzmann constant? Which one of the following is the remaining grade of paper used in paper capacitor, besides the other two grade of paper-low and extra low loss? |
| A. | Strong dielectric |
| B. | Regular |
| C. | Rough |
| D. | High loss |
| Answer» C. Rough | |
| 2866. |
When a p-n junction is forward biased, the current remains zero till the applied voltage overcomes the barrier potential. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2867. |
The carrier mobility in a semiconductor is 0.4 m2/Vs. Its diffusion constant at 300k will be (in m2/s). |
| A. | 0.43 |
| B. | 0.16 |
| C. | 0.04 |
| D. | 0.01 |
| Answer» C. 0.04 | |
| 2868. |
During induction heating of metals which of the following is abnormally high? |
| A. | Frequency |
| B. | Voltage |
| C. | Current |
| D. | Power factor |
| Answer» B. Voltage | |
| 2869. |
Assertion (A): Alkali metals are used as emitters in phototubes. Reason (R): Alkali metals have low work functions. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 2870. |
In P-N junction, the region containing the uncompensated acceptor and donor ions is called |
| A. | transition zone |
| B. | depletion region |
| C. | neutral region |
| D. | active region |
| Answer» C. neutral region | |
| 2871. |
In a photodiode the current is due to |
| A. | majority carriers |
| B. | minority carriers |
| C. | both majority and minority carriers |
| D. | either (a) or (b) |
| Answer» C. both majority and minority carriers | |
| 2872. |
Consider the following statements Acceptor level lies close the valence band.Donor level lies close to the valence band.n type semiconductor behaves as an insulator at 0 K.p type semiconductor behaves as an insulator at 0 K. Of these statements: |
| A. | 2 and 3 are correct |
| B. | 1 and 3 are correct |
| C. | 1 and 4 are correct |
| D. | 3 and 4 are correct |
| Answer» D. 3 and 4 are correct | |
| 2873. |
If the temperature of on extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then |
| A. | the majority carrier density doubles |
| B. | the minority carrier density doubles |
| C. | the minority carrier density becomes 4 times the original value |
| D. | both majority and minority carrier densities double |
| Answer» E. | |
| 2874. |
Assertion (A): The conductivity of an n type semiconductor increases with increase in temperature and increase in density of donor atoms. Reason (R): Diffusion of carriers occurs in semiconductors. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 2875. |
The early effect in a BJT is caused by |
| A. | fast turn on |
| B. | fast turn off |
| C. | large collector base reverse bias |
| D. | large emitter base forward bias |
| Answer» D. large emitter base forward bias | |
| 2876. |
Assertion (A): In active region of CE output characteristics of BJT, collector current is nearly constant. Reason (R): Base current in CE connection is very small. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 2877. |
If for a silicon n-p-n transistor, the base to emitter voltage (VBE) is 0.7 V and the collector to base voltage VCB is 0.2 Volt, then the transistor is operating in the |
| A. | normal active mode |
| B. | saturation mode |
| C. | inverse active mode |
| D. | cut off mode |
| Answer» B. saturation mode | |
| 2878. |
The number of doped regions in a bipolar junction transistor is |
| A. | 1 |
| B. | 2 |
| C. | 3 |
| D. | 4 |
| Answer» D. 4 | |
| 2879. |
Donor energy level is n type semiconductor is very near valence band. |
| A. | True |
| B. | False |
| Answer» C. | |
| 2880. |
GaAs has an energy gap 1.43 eV the optical cut off wavelength of GaAs would lie in the |
| A. | visible region of the spectrum |
| B. | infrared region of the spectrum |
| C. | ultraviolet region of the spectrum |
| D. | for ultraviolet region of the spectrum |
| Answer» C. ultraviolet region of the spectrum | |
| 2881. |
Electrons can be emitted from a metal surface due to high electric field. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2882. |
In an n type semiconductor the fermi level is 0.35 eV below the conduction band, the concentration of donor atoms is increased to three times. The new position of Fermi level will be |
| A. | 0.35 eV below conduction band |
| B. | about 0.32 eV below conduction band |
| C. | about 0.32 eV above conduction band |
| D. | about 0.1 eV below conduction band |
| Answer» C. about 0.32 eV above conduction band | |
| 2883. |
Assertion (A): In a BJT, the base region is very thick. Reason (R): In p-n-p transistor most of holes given off by emitter diffuse through the base. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» E. | |
| 2884. |
Assertion (A): The behaviour of FET is similar to that of a pentode. Reason (R): FETs and vacuum triode are voltage controlled devices. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 2885. |
SCR can be turned on by applying anode voltage at a sufficient fast rateapplying sufficiently large anode voltageincreasing the temperature of SCR to a sufficientlyapplying sufficiently large gate current. |
| A. | 1, 2, 4 only |
| B. | 4 only |
| C. | 1, 2, 3, 4 |
| D. | none |
| Answer» D. none | |
| 2886. |
The derating factor for a BJT transistor is about |
| A. | 0.5 mW/ C |
| B. | 2.5 mW/ C |
| C. | 10 mW/ C |
| D. | 25 mW/ C |
| Answer» C. 10 mW/ C | |
| 2887. |
Assertion (A): When reverse voltage across a p-n junction is increased, the junction capacitance decreases. Reason (R): Capacitance of any layer is inversely proportional to thickness. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 2888. |
An intrinsic silicon sample has 2 million free electrons. The number of holes in the sample is |
| A. | 2 million |
| B. | almost zero |
| C. | more than 2 million |
| D. | less than 2 million |
| Answer» B. almost zero | |
| 2889. |
In an n type semiconductor |
| A. | number of free electrons and holes are equal |
| B. | number of free electrons is much greater than the number of holes |
| C. | number of free electrons may be equal or less than the number of holes |
| D. | number of holes is greater than the number of free electrons |
| Answer» C. number of free electrons may be equal or less than the number of holes | |
| 2890. |
Mobility of electrons and holes are equal. |
| A. | True |
| B. | False |
| Answer» C. | |
| 2891. |
A Varactor diode has |
| A. | a fixed capacitance |
| B. | a fixed inductance |
| C. | a voltage variable capacitance |
| D. | a current variable inductance |
| Answer» D. a current variable inductance | |
| 2892. |
The most important set of specifications of transformer oil includes |
| A. | dielectric strength and viscosity |
| B. | dielectric strength and flash point |
| C. | flash point and viscosity |
| D. | dielectric strength, flash point and viscosity |
| Answer» E. | |
| 2893. |
Assertion (A): In Hall effect the O.C. transverse voltage developed by a current carrying semiconductor with a steady magnetic field perpendicular to the current direction has opposite signs for n and p semiconductors. Reason (R): The magnetic field pushes both holes and electrons in the same direction. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 2894. |
The breakdown voltage in a zener diode |
| A. | is almost constant |
| B. | is very small |
| C. | may destroy the diode |
| D. | decreases with increase in current |
| Answer» B. is very small | |
| 2895. |
One eV = 1.602 x 10-19 joules. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 2896. |
A varactor diode is used for |
| A. | tuning |
| B. | rectification |
| C. | amplification |
| D. | rectification and amplification |
| Answer» B. rectification | |
| 2897. |
Assertion (A): When VDS is more than rated value the drain current in a JFET is very high. Reason (R): When VDS is more than rated value, avalanche breakdown occurs. |
| 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 a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 2898. |
If ib is plate current, eb is plate voltage and ec is grid voltage the v-i curve of a vacuum triode is ib = 0.003 (eb + kec)n. Typical values of k and n are |
| A. | 0.5 and 1 |
| B. | - 2 and 1 |
| C. | 30 and 1 |
| D. | 30 and 1.5 |
| Answer» E. | |
| 2899. |
In which material do conduction and valence bands overlap |
| A. | insulators |
| B. | conductors |
| C. | both conductor and semiconductor |
| D. | semiconductors |
| Answer» C. both conductor and semiconductor | |
| 2900. |
For a photoconductor with equal electron and hole mobilities and perfect ohmic contacts at the ends, an increase in illumination results in |
| A. | a change in O.C. voltage |
| B. | a change in S.C. current |
| C. | a decrease in resistance |
| D. | an increase in resistance |
| Answer» D. an increase in resistance | |