question_answer 1)
In an n-type silicon, which of the following statement is true:
A)
Electrons are majority carriers and trivalent atoms are the dopants. done
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B)
Electrons are minority carriers and pentavalent atoms are the dopants. done
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C)
Holes are minority carriers and pentavalent atoms are the dopants. done
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D)
Holes are majority carriers and tiivalent atoms are the dopants. done
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question_answer 2)
Carbon, silicon and germanium have four valence electrons each. These are characterised by valence and conduction bands separated by energy band gap respectively equal to \[{{({{E}_{g}})}_{C,}}{{({{E}_{g}})}_{Si}}\] and \[{{({{E}_{g}})}_{Ge}}\] Which of the following statements is true?
A)
\[{{({{E}_{g}})}_{Si}}<{{({{E}_{g}})}_{Ge}}<{{({{E}_{g}})}_{C}}\] done
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B)
\[{{({{E}_{g}})}_{C}}<{{({{E}_{g}})}_{Ge}}>{{({{E}_{g}})}_{Si}}\] done
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C)
\[{{({{E}_{g}})}_{C}}>{{({{E}_{g}})}_{Si}}>{{({{E}_{g}})}_{Ge}}\] done
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D)
\[{{({{E}_{g}})}_{C}}={{({{E}_{g}})}_{Si}}={{({{E}_{g}})}_{Ge}}\] done
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question_answer 3)
The conductivity of a semiconductor increases with increase in temperature because
A)
number density of free current carriers increases. done
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B)
relaxation time increases. done
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C)
both number density of carriers and relaxation time increase. done
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D)
number density of current carriers increases: relaxation time decreases but effect of decrease in relaxation time is much less than the increase in number density. done
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question_answer 4)
Hole is
A)
an anti-particle of electron. done
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B)
a vacancy created when an electron leaves a covalent bond. done
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C)
absence of free electrons. done
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D)
an artificially created particle. done
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question_answer 5)
Semiconductors behave like insulators at ____
A)
\[{{0}^{o}}C\] done
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B)
0 K done
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C)
273 K done
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D)
None of the above done
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question_answer 6)
When the conductivity of a semiconductor is due to rupture of its covalent bond only then the semiconductor is called
A)
Intrinsic done
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B)
Extrinsic done
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C)
Donor done
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D)
acceptor done
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question_answer 7)
Tetra valent semiconductor is to be doped with __ valent element to achieve ___ type extrinsic semiconductor.
A)
penta, n done
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B)
tri, p done
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C)
penta, p done
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D)
both [a] and [b] done
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question_answer 8)
In an unbiased p-n junction, holes diffuse from the p-region to n-region because
A)
free electrons in the n-region attract them. done
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B)
they move across the junction by the potential difference. done
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C)
hole concentration in p-region is more as compared to n-region. done
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D)
All the above. done
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question_answer 9)
When a forward bias is applied to a p-n junction, it
A)
raises the potential barrier. done
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B)
reduces the majority carrier current to zero. done
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C)
lowers the potential barrier. done
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D)
None of the above done
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question_answer 10)
In Figure, \[{{V}_{\operatorname{o}}}\] is the potential barrier across a p-n junction, when no battery is connected across the junction
A)
1 and 3 both correspond to forward bias of junction done
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B)
3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction done
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C)
1 corresponds to forward bias and 3 corresponds to reverse bias of junction. done
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D)
3 and 1 both correspond to reverse bias of junction. done
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question_answer 11)
In Figure, assuming the diodes to be ideal,
A)
\[{{\operatorname{D}}_{1}}\] is forward biased and \[{{\operatorname{D}}_{2}}\] is reverse biased and hence current flows from A to B done
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B)
\[{{\operatorname{D}}_{2}}\] is forward biased and \[{{\operatorname{D}}_{1}}\] is reverse biased and hence no current flows from B to A and vice versa. done
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C)
\[{{\operatorname{D}}_{1}}\] and \[{{\operatorname{D}}_{2}}\] are both forward biased and hence current flows from A to B. done
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D)
\[{{\operatorname{D}}_{1}}\] and \[{{\operatorname{D}}_{2}}\] are both reverse biased and hence no current flows from A to B and vice versa. done
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question_answer 12)
A 220 V A.C. supply is connected between points A and B in Figure. What will be the potential difference V across the capacitor?
A)
220 V done
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B)
110 V done
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C)
0 V done
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D)
220\[\sqrt{2}\] V done
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question_answer 13)
The output of the given circuit in Figure
A)
would be zero at all times. done
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B)
would be like a half wave rectifier with positive cycles in output. done
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C)
would be like a half wave rectifier with negative cycles in output. done
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D)
would be like that of a full wave rectifier. done
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question_answer 14)
In the circuit shown in Figure, if the diode forward voltage drop is 0.3 V, the voltage difference between A and B is
A)
1.3 V done
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B)
2.3 V done
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C)
0 V done
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D)
0.5 V done
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question_answer 15)
Which one of the following diagrams depicts the proper flow or electrons and holes in a forward biased p-n junction diode?
A)
B)
C)
D)
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