This contains most important and most asked Basic Electronics multiple choice questions. Containing mcqs of topic Diode Circuits.
Before solving this questions I suggest you must read this basic electronics
Diode Circuits
1.The process by which impurities are added to a pure semiconductor is
a. Diffusing
b. Drift
c. Doping
d. Mixing
Ans: c
2.When an atom gains or losses an ion it is said to be
a. Ionised
b. Bonded
c. Excited
d. stabilized
Ans: a
3.Barrier potential for silicon diode
a. 0.3
b. 0.4
c. 0.7
d. 0.1
Ans: c
4.The manufacturer of diode provides the detail information about diode, in the form of
a. excel sheet
b. Data Sheet
c. Log sheet
d. None of above
Ans: b
5. In a semiconductor, the energy gap between valence band and conduction band is about………
a. 5 eV
b. 10 eV
c. 15 eV
d. 1 eV
Ans: d
6.A semiconductor diode has forward resistance of the order of ……….
a. Ω
b. KΩ
c. MΩ
d. none of the above
Ans: a
7.The reverse current in a diode is of the order of …………….
a. μA
b. mA
c. A
d. KA
Ans: a
8.A reverse-biased diode acts like
a. open switch
b. closed switch
c. small resistance
d. none of the above
Ans: a
9.The potential barrier at a PN-junction is due to the charges on either side of the junction. These charges are…..
a. minority carriers
b. majority carriers
c. both majority and minority carriers
d. fixed donor and acceptor ions
Ans: d
10.When we apply reverse bias to a junction diode, it
a. lowers the potential barrier
b. raises the potential barrier
c. greatly increases the minority-carrier current
d. greatly increases the majority-carrier current
Ans: b
11.The turn-on voltage of a Ge junction diode is nearly….. volts.
a. 0.7
b. 0.3
c. 1
d. 0.1
Ans: b
12.If a pure silicon crystal has one million free electrons inside it, how many holes does it have?
a. One million
b. two million
c. zero
d. ten million
Ans: a
13.A strong electric field across a P-N junction that causes covalent bond to break apart is called
a. avalanche breakdown
b. reverse breakdown
c. Zener Breakdown
d. Low voltage break down
Ans: c
14.Resistivity of semiconductor depends on…
a. shape of the semiconductor
b. atomic nature of semiconductor
c. width of semiconductor
d. length of semiconductor
Ans : b
15.At room temperature, the current in the intrinsic semiconductor is due to....
a. Holes
b. electrons
c. Ions
d. holes and electrons
Ans : d
16.If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then
a. The majority carrier density doubles
b. the minority carrier density is doubled
c. the minority carrier density becomes 4 times the original value
d. both majority and minority carrier densities double
Ans : c
17.When holes leave the p-material to fill electrons in the n-material the process is called
a. Mixing
b. Depletion
c. Diffusion
d. Depletion
Ans : c
18.Diffusion current in the diode is caused by
a. Chemical energy
b. heat energy
c. voltage
d. crystal formation
Ans : a
19. Depletion region in a pn diode is due to
a. reverse biasing
b. forward biasing
c. an area created by crystal doping
d. an area void of current carriers
Ans: a
20.When a diode is forward biased
a. Barrier potential increases
b. Barrier potential decreases
c. Majority current reduces
d. Minority current reduces
Ans: b
21.The p-n junction forms device called
a. Triac
b. Diode
c. multiplexer .
d. Semiconductor
Ans: b
22.The normal forward biased operation of diode is
a. Below the knee point
b. at the origin
c. above knee point
d. all the above
Ans: c
23. In diode reverse current is due to
a. Mobile donor ionsb. Mobile acceptor ions
c. minority carriers
d. majority carriers
Ans: c
24.Reverse characteristic of diode is plotted in
a. 1st Quadrant
b. 2nd Quadrant
c. 3rd Quadrant
d. 4th Quadrant
Ans: c
25.In an unbiased PN-junction, the junction current at equilibrium is
a. due to diffusion of minority carriers only
b. due to diffusion of majority carriers only
c. zero, because equal but opposite carriers are crossing the junction
d. zero, because no charges are crossing the junction
Ans: c
26.In a PN-junction diode, holes diffuse from the P region to the N region because
a. the free electrons in the N region attract them
b. they are swept across the junction by the potential difference
c. there is greater concentration of holes in the P region as compared to N region
d. none of the above
Ans: c
27.The number of minority carriers crossing the junction of a diode depends primarily on the
a. concentration of doping impurities
b. magnitude of the potential barrier
c. magnitude of the forward-bias voltage d. rate of thermal generation of electron –hole pairs
Ans: d
28.The forward bias applied to a PN- junction diode is increased from zero to higher values. Rapid increase in the current flow for a relatively small increase in voltage occurs
a. immediately
b. only after the forward bias exceeds the potential barrier
c. when the flow of minority carriers is sufficient to cause an avalanche breakdown
d. when the depletion area becomes larger than the space-charge area
Ans: b
29.If the arrow of a semiconductor diode symbol is positive w.r.t. bar, then diode is…..biased.
a. reverse
b. forward
c. none of the two
d. forward or reverse
Ans: b
30.The leakage current in a semiconductor diode is due to…….
a. minority carriers
b. majority carriers
c. junction capacitance
d. none of the above
Ans: a
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