Semiconductor Electronics: Materials, Devices and Simple Circuits Test 52

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Semiconductor Electronics: Materials, Devices and Simple Circuits Test 52

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Question 1
1 / -0

Two conducting wires of same material and of equal lengths, resistance and resistivity having ratio $$1:2$$. Their diameter ratio will be

A
$$1:2$$

B
$$1:4$$

C
$$4:1$$

D
$$1:\sqrt{2}$$

Solution

Hence, option $$(D)$$ is correct answer.
Question 2
1 / -0

In a semiconductor

A
There are no free electrons at any temperature

B
The number of free electrons is more than in a conductor

C
There is no free electrons at OK

D
None of these

Solution

In semiconductor, no free electron at normal temperature.
Hence,
option $$C$$ is correct answer.
Question 3
1 / -0

With rise in temperature the electrical conductivity of intrinsic semiconductor:

A
increases

B
decreases

C
first increases and then decreases

D
first decreases and then increases

Solution

In an intrinsic semiconductor, the gap between the valence band and the conduction band is minimal. The electrons residing in the valence band can acquire energy and jump to the conduction band. When a semiconductor’s temperature increases, it increases the electrons’ energy, resulting in increased conductivity of the intrinsic semiconductor.
Question 4
1 / -0

Wire $$P$$ and $$Q$$ have the same resistance at a ordinary room temperature .When heated resistance at a ordinary room temperature .When heated resistance of $$P$$ increases and that of $$Q$$ decreases. we conclude that

A
$$P$$ is semiconductor and $$Q$$ is conductor

B
$$P$$ is conductor and $$Q$$ is semiconductor

C
$$P$$ is n-type semiconductor and $$Q$$ is $$p-$$ type conductor

D
None of the above

Solution

Conductor has positive temperature coefficient of resistance but semiconductor has negative temperature coefficient of resistance. Hence, $$P$$ is semiconductor and $$Q$$ is conductor.
Question 5
1 / -0

The width of deplection layer in P-N junction diode is :

A
$$10^-3$$ m

B
$$10^-4$$ m

C
$$10^-5$$ m

D
$$10^-6$$ m

Solution

In general cases, the magnitude width of the depletion region of a $${\text{p - n}}$$ junction that is used in experiments and in other places is $$1 \times {10^{ - 5}}m$$.
Question 6
1 / -0

In a common emitter transistor the current gain is 80. What is change in collector current, when change in base current is $$250\mu A$$

A
$$9 \times {10^{ - 2}}A$$

B
$$8 \times {10^{ - 6}}A$$

C
$$2 \times {10^{ - 2}}A$$

D
$$3 \times {10^{ - 7}}A$$

Solution

$$\begin{array}{l} Current\, \, given=\beta =\frac { { \Delta { i_{ e } } } }{ { \Delta { i_{ b } } } } \\ \Rightarrow \Delta { i_{ e } }=\beta \times \Delta { i_{ b } } \\ =80\times 20\mu A \\ =2\times { 10^{ -2 } }A \end{array}$$
Hence,
option $$(C)$$ is correct answer.
Question 7
1 / -0

Symbolic representation of photodiode is

A

B

C

D

Solution

In photodiode, it is illuminated by light radiations, which in turn produces electric current.
Question 8
1 / -0

In the forward bias characteristic curve, a diode appears as :

A
an OFF switch

B
a high resistance

C
an ON switch

D
a capacitor

Solution

Diode allows the current to pass through it when it is forward biased.
In the forward biased characteristics curve, a diode appears as an ON switch.
Question 9
1 / -0

A two-input NAND gate is followed by a single-input NOR gate. This logic circuit will function as :

A
an opposite to AND gate

B
an OR gate

C
a NOT gate

D
a NOR gate

Solution

The equivalent logic of the whole system can be written as $$\overline {\left( {\overline {\text{A}} {\text{ }}.{\text{ }}\overline {\text{B}} } \right)} $$
$${\text{A B }}\left( {\overline {\text{A}} {\text{ }}{\text{. }}\overline {\text{B}} } \right)$$
$${\text{1 1 0}}$$
$${\text{0 0 1}}$$
$${\text{1 0 1}}$$
$${\text{0 1 1}}$$
Clearly, this works like a OR-gate.
The option (B) is correct.
Question 10
1 / -0

In a $$\mathrm { n }$$ -p-n transistor circuit, the collector current is $$10 \mathrm { mA }$$ . If $$95$$ percent of the electrons emitted reach the collector, which of the following statements are true?

A
The emitter current will be 8$$\mathrm { mA }$$

B
The base current will be $$2 \mathrm { mA }$$

C
The base current will be $$ 0.53\mathrm { mA }$$

D
None of these

Solution