Semiconductor Electronics: Materials, Devices and Simple Circuits Test 47

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Semiconductor Electronics: Materials, Devices and Simple Circuits Test 47

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Weekly Quiz Competition

Question 1
1 / -0

In the following circuits, PN-junction diodes Dl, D2 and D3 are ideal for the following potential of AB, the correct increasing order of resistance between A and B will be -

A
$$( i ) < ( i i ) < ( i i i )$$

B
$$\text { (iii) } < \text { (ii) } < \text { (i) }$$

C
$$\text { (ii) } = \text { (iii) } < \text { (i) }$$

D
$$\text { (i) } = \text { (iii) } < \text { (ii) }$$
Question 2
1 / -0

The output Y of the combination of gates shown is equal to:

A
A

B
$$\bar { A } $$

C
A+B

D
AB

Solution

Here,

$$Y=A.(A+B)$$

$$Y=A.A+A.B$$

$$Y=A+A.B$$

$$Y=A.(1+B)$$

$$Y=A.1$$

$$Y=A$$

Option $$\textbf A$$ is the correct answer
Question 3
1 / -0

In a silicon diode, the reverse current increases from $$10\mu A$$ to $$20\mu A$$. when the reverse voltage change from $$2V$$ to $$4V$$. The reverse ac resistance of the diode is

A
$$1\times 10^{5}\ \Omega$$

B
$$3\times 10^{5}\ \Omega$$

C
$$2\times 10^{5}\ \Omega$$

D
$$4\times 10^{5}\ \Omega$$

Solution

change in current $$ = 20\mu A-10\mu A = 10\mu A $$
change in voltage $$ = hv-2v = 2v $$
reverse ac resistance $$ R = \frac{V}{2} $$
$$ = \dfrac{2}{10\mu A} = 2\times 10^{5}\Omega $$
Question 4
1 / -0

How many NOR gates are required to form NAND gate:

A
$$1$$

B
$$3$$

C
$$2$$

D
$$4$$

Solution

4 NOR gates required to form NAND gate.

2 NOR gates with signle inputs for input

1 NOR gate for output

1 NOR gate to convert AND to NAND.
Question 5
1 / -0

A two inputed XOR gate produces an high output only when its both inputs are:

A
same

B
different

C
low

D
high

Solution
Question 6
1 / -0

When all the inputs of a NAND gate are connected together, the resulting circuit is:

A
a NOT gate

B
an AND gate

C
an OR gate

D
a NOR gate

Solution

The equation of NAND gate is
$$Y=\bar{A}.\bar{B}$$

When both the terminals are connected together.

$$A=B=A$$

$$Y=\bar{A}.\bar{A} =\bar{A}. \bar{A}=\bar{A}$$

Which is nothing but the equation of NOT gate.

$$Y=\bar{A}$$

Option $$\textbf A$$ is the correct answer
Question 7
1 / -0

In a zener diode, break down occurs in reverse bias due to

A
Impact ionisation

B
Internal field emission

C
High doping concentration

D
All of these

Solution
Question 8
1 / -0

In the adjacent circuit, A and B represent two inputs and C represents the output. The circuit represents.

A
NOR gate

B
AND gate

C
NAND gate

D
OR gate

Solution

Relation between input and output
A and B are input
Y is out put. This circuit represents OR gate
Question 9
1 / -0

A.P.N junction Diode when connected to an AC sourice behaves as an ?

A
Rectifier

B
Zero resistance

C
Amplifier

D
None of these

Solution

When a diode is connected across AC source, it works as both half and full wave rectifier. Because for positive half of cycle it allows the current to flow but for negative half of cycle it stops current to flow.
Question 10
1 / -0

If electromagnetic rays are incident on a semiconductors its conductivity .

A
Increases

B
Increases with increases frequency

C
Increases when frequency increases above certain frequency

D
Increases when wavelength is increases above a certain wavelength

Solution

The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it.