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MCQOPTIONS
This section includes 1017 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 851. |
The band gap of Si at room temperature is |
| A. | 1.3 eV |
| B. | 0.7 eV |
| C. | 1.1 eV |
| D. | 1.4 eV |
| Answer» D. 1.4 eV | |
| 852. |
In an n channel JFET, the gate is |
| A. | n type |
| B. | p type |
| C. | either n or p |
| D. | partially n & partially p |
| Answer» C. either n or p | |
| 853. |
Gel is |
| A. | a polymer having side groups distributed randomly along a vinly polymer chain |
| B. | a polymer having secondary chains branching from the main molecular chain |
| C. | a solid frame work of colloidal particles linked together and containing a fluid |
| D. | a polymer in which the repeating unit of each molecule has vinyl group |
| Answer» D. a polymer in which the repeating unit of each molecule has vinyl group | |
| 854. |
In which region of a CE bipolar transistor is collector current almost constant? |
| A. | Saturation region |
| B. | Active region |
| C. | Breakdown region |
| D. | Both saturation and active region |
| Answer» C. Breakdown region | |
| 855. |
When a p-n Junction is forward biased |
| A. | the current flow is due to electrons only |
| B. | the majority carriers in both p and n materials are driven toward the junction. |
| C. | the majority carriers in both p and n materials are away from the junction. |
| D. | both (a) and (c). |
| Answer» C. the majority carriers in both p and n materials are away from the junction. | |
| 856. |
The skin depth of copper is found to be 66 mm at 1 MHz at a certain temperature. At the same temperature and at 2 MHz, the skin depth would be approximately |
| A. | 47 μm |
| B. | 33 μm |
| C. | 92 μm |
| D. | 1.22 μm |
| Answer» B. 33 Œºm | |
| 857. |
The v-i characteristics of a FET is shown in figure. In which region is the device biased for small signal amplification |
| A. | AB |
| B. | BC |
| C. | CD |
| D. | BD |
| Answer» C. CD | |
| 858. |
In a specimen of n type semiconductor, the initial concentration of holes and electrons is pno and nno. When the specimen is subjected to radiation, the hole and electron concentration increase to pn and nn. Then |
| A. | pn - pno = nn - nno |
| B. | pn + pno = nn + nno |
| C. | pn - pno = nno + nno |
| D. | pn + pno = nn - pno |
| Answer» B. pn + pno = nn + nno | |
| 859. |
In order to achieve good stabilization in potential divider method current I1 through R1 and R2 should be |
| A. | I1 > 20 IB |
| B. | I1 > 15 IB |
| C. | I1 < 5 IB |
| D. | I1 > 10 IB |
| Answer» E. | |
| 860. |
When a ferromagnetic substance is magnetised, small changes in dimensions occur. Such a phenomenon is known as |
| A. | magnetic hystresis |
| B. | magnetic expansion |
| C. | magneto striction |
| D. | magneto calorisation |
| Answer» D. magneto calorisation | |
| 861. |
The diameter of an atom is |
| A. | 10-6 metre |
| B. | 10-10 metre |
| C. | 10-15 metre |
| D. | 10-21 metre |
| Answer» C. 10-15 metre | |
| 862. |
Resistivity of electrical conductors is most affected by |
| A. | Pressure |
| B. | temperature |
| C. | composition |
| D. | ageing |
| Answer» C. composition | |
| 863. |
In a zener diode |
| A. | the forward current is very high |
| B. | sharp breakdown occurs at a certain reverse voltage |
| C. | the ratio v-i can be negative |
| D. | there are two p-n junctions |
| Answer» C. the ratio v-i can be negative | |
| 864. |
The number of valence electrons in a silicon atom is |
| A. | 4 |
| B. | 2 |
| C. | 1 |
| D. | 0 |
| Answer» B. 2 | |
| 865. |
An increase of reverse voltage decreases the junction capacitance. |
| A. | 1 |
| B. | |
| C. | 1 A to 10 A |
| D. | 0.1 A to 1 A |
| Answer» B. | |
| 866. |
The electron and hole concentration in a intrinsic semiconductor are ni and Pi respectively when doped with a P type material, these change to n and P, respectively. Then |
| A. | n + P = ni + Pi |
| B. | n + ni = P + Pi |
| C. | nPi = niP |
| D. | nP = ni Pi |
| Answer» E. | |
| 867. |
Hall effect can be used |
| A. | to find type of semiconductor (whether p or n) |
| B. | to find carrier concentration |
| C. | to measure conductivity |
| D. | all of the above |
| Answer» E. | |
| 868. |
A potential of 7 V is applied to a silicon diode. A resistance of 1 K ohm is also in series with the diode. The current is |
| A. | 7 mA |
| B. | 6.3 mA |
| C. | 0.7 mA |
| D. | 0 |
| Answer» C. 0.7 mA | |
| 869. |
The energy of one quantum of light equal to hf. |
| A. | 1 |
| B. | |
| C. | 0.1 eV |
| D. | 2 eV |
| Answer» B. | |
| 870. |
The output v-i characteristics of enhancement type MOSFET has |
| A. | only an ohmic region |
| B. | only a saturation region |
| C. | an ohmic region at low voltage value and a saturation region at high voltage |
| D. | a saturation region at low voltage value and an ohmic region at high voltage |
| Answer» D. a saturation region at low voltage value and an ohmic region at high voltage | |
| 871. |
If 100 V is the peak voltage across the secondary of the transformer in a half-wave rectifier (without any filter circuit), then the maximum voltage on the reverse-biased diode is |
| A. | 200 V |
| B. | 141.4 V |
| C. | 100 V |
| D. | 86 V |
| Answer» C. 100 V | |
| 872. |
Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20°C and 32 nA at 50°C. Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10°C rise in temperature. |
| 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 | |
| 873. |
Fermi level is the amount of energy in which |
| A. | a hole can have at room temperature |
| B. | an electron can have at room temperature |
| C. | must be given to an electron move to conduction band |
| D. | none of the above |
| Answer» D. none of the above | |
| 874. |
Which of the following is basically a voltage controlled capacitance? |
| A. | Zener diode |
| B. | Diode |
| C. | Varactor diode |
| D. | LED |
| Answer» D. LED | |
| 875. |
Holes act like |
| A. | positive charges |
| B. | neutral atoms |
| C. | negative charges |
| D. | crystals |
| Answer» B. neutral atoms | |
| 876. |
The forbidden band in semiconductors is of the order of |
| A. | 6 eV |
| B. | 1 eV |
| C. | 10 eV |
| D. | 0.01 eV |
| Answer» C. 10 eV | |
| 877. |
The amount of photoelectric emission current depends on the frequency of incident light. |
| A. | 1 |
| B. | |
| C. | the width of depletion layer increases |
| D. | the width of depletion layer decreases |
| Answer» C. the width of depletion layer increases | |
| 878. |
For an n-channel enhancement type MOSFET, if the source is connected at a higher potential than that of the bulk (VSB > 0), the threshold voltage VT of the MOSFET will |
| A. | remain unchanged |
| B. | decrease |
| C. | change Polarity |
| D. | increase |
| Answer» B. decrease | |
| 879. |
The sensitivity of human eyes is maximum at |
| A. | white portion of spectrum |
| B. | green portion of spectrum |
| C. | red portion of spectrum |
| D. | violet portion of spectrum |
| Answer» C. red portion of spectrum | |
| 880. |
In CE connection, the leakage current of a transistor is about |
| A. | 10 x 10-9 A |
| B. | 5 x 10-6 A |
| C. | 200 x 10-6 A |
| D. | 5 x 10-3 A |
| Answer» D. 5 x 10-3 A | |
| 881. |
In which of the following case the rating of the transformer to deliver 100 watts of d.c. power to a load, will be least? |
| A. | Half wave rectifier |
| B. | Full wave rectifier |
| C. | Bridge type full wave rectifier |
| D. | Three phase full wave rectifier |
| Answer» E. | |
| 882. |
The word enhancement mode is associated with |
| A. | tunnel diode |
| B. | MOSFET |
| C. | JFET |
| D. | photo diode |
| Answer» C. JFET | |
| 883. |
The conductivity of materials found in nature ranges from 109 ohm-1m-1 to nearly 1018 ohm-1 m-1 from this it can be concluded that the conductivity of silicon in ohm-1 cm-1 will be nearly |
| A. | 0.5 x 10-15 |
| B. | 0.5 x 10-21 |
| C. | 0.5 x 10-12 |
| D. | 0.5 x 10-3 |
| Answer» E. | |
| 884. |
The density of states (i.e. number of states per eV per m3) in the conduction band for energy level E is proportional to |
| A. | E |
| B. | E |
| C. | E1.5 |
| D. | E2 |
| Answer» B. E | |
| 885. |
In intrinsic semiconductor magnitude of free electron and hole concentrations are equal. |
| A. | 1 |
| B. | |
| C. | high resistance in forward as well as reverse direction |
| D. | low resistance in forward as well as reverse direction |
| Answer» B. | |
| 886. |
Photoelectric emitters in photo tubes are generally made of |
| A. | alkali metals |
| B. | metals |
| C. | semiconductors |
| D. | metal and semiconductors |
| Answer» B. metals | |
| 887. |
For a NPN bipolar transistor, what is the main stream of current in the base region? |
| A. | Drift of holes |
| B. | Diffusion of holes |
| C. | Drift of electrons |
| D. | Diffusion of electrons |
| Answer» C. Drift of electrons | |
| 888. |
The resistivity of a semiconductor |
| A. | increases as the temperature increases |
| B. | decreases as the temperature increases |
| C. | remains constant even when temperature varies |
| D. | none of the above |
| Answer» C. remains constant even when temperature varies | |
| 889. |
Assertion (A): When Diode used as rectifier the reverse breakdown voltage should not be exceeded. Reason (R): A high inverse voltage can destroy a p-n junction. |
| 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 | |
| 890. |
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 | |
| 891. |
When a voltage is applied to a semiconductor crystal then the free electrons will flow. |
| A. | towards positive terminal |
| B. | towards negative terminal |
| C. | either towards positive terminal or negative terminal |
| D. | towards positive terminal for 1 μs and towards negative terminal for next 1 μs |
| Answer» B. towards negative terminal | |
| 892. |
The drain characteristics of JFET in operating region, are |
| A. | inclined upwards |
| B. | almost flat |
| C. | inclined downwards |
| D. | inclined upwards or downwards |
| Answer» C. inclined downwards | |
| 893. |
Assertion (A): At room temperature the fermi level in p type semiconductor lies nearer to the valence band and in n type semiconductor it lies nearer to the conduction band. Reason (R): At room temperature, the p type semiconductor is rich in holes and n type semiconductor is rich in electrons. |
| 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 | |
| 894. |
Peak inverse voltage will be highest for |
| A. | half wave rectifier |
| B. | full wave rectifier |
| C. | bridge rectifier |
| D. | three phase full wave rectifier |
| Answer» C. bridge rectifier | |
| 895. |
When a diode is forward biased, the diode current is |
| A. | high |
| B. | low |
| C. | zero |
| D. | low or zero |
| Answer» B. low | |
| 896. |
In the fabrication of n-p-n transistor in an IC, the buried layer on the P-type substrate is |
| A. | P+ -doped |
| B. | n+ -doped |
| C. | used to reduce the parasitic capacitance |
| D. | located in the emitter region |
| Answer» D. located in the emitter region | |
| 897. |
The Ni-Zn ferrites are used for audio and TV transformers is that |
| A. | they have large saturation magnetisation |
| B. | they are easy to fabricate by rolling |
| C. | they are free from pores and voids |
| D. | they have high electro-resistivity |
| Answer» B. they are easy to fabricate by rolling | |
| 898. |
A full wave bridge rectifier is supplied voltage at 50 Hz. The lowest ripple frequency will be |
| A. | 400 Hz |
| B. | 200 Hz |
| C. | 100 Hz |
| D. | 50 Hz |
| Answer» D. 50 Hz | |
| 899. |
Higher value of ripple factor indicates |
| A. | poor rectification |
| B. | ideal rectification |
| C. | r.m.s. value to peak value |
| D. | none of the above |
| Answer» B. ideal rectification | |
| 900. |
Magnetic recording tape is most commonly made from |
| A. | small particles of iron |
| B. | silicon iron |
| C. | ferric-oxide |
| D. | silver nitrate |
| Answer» D. silver nitrate | |