Semiconductor Electronics: Materials, Devices and Simple Circuits Test 71

Result

Semiconductor Electronics: Materials, Devices and Simple Circuits Test 71

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Question 1
1 / -0

The band diagrams of three semiconductors are given in the figure. From left to right they are respectively.

A
n-intrinsic-p

B
p-intrinsic-n

C
intrinsic-p-n

D
intrinsic-n-p

Solution

In the diagrams $${\text{C}}$$, $${\text{V}}$$ & $${\text{Ef}}$$ represents the conduction band, the valence band, and the Fermi level.
For $${\text{n - }}$$type semiconductor, the Fermi level is near the conduction band.
For $${\text{p - }}$$type semiconductor, the Fermi level is near the valence band.
For intrinsic semiconductor, the Fermi level lies in the middle.
Question 2
1 / -0

Given: $$A$$ and $$B$$ are input terminals.
Logic $$1\, = \, > \, 5\, V$$
Logic $$0\, = \, < \, 1\, V$$
Which logic gate operation, the above circuit does?

A
AND gate

B
OR gate

C
XOR gate

D
NOR gate

Solution
Question 3
1 / -0

A cube of germanium is placed between the poles of a magnet and a voltage is applied across opposite faces of the cube as shown in Figure. The magnetic field is directed vertical downward in the plane of the paper:
What effect will occur at the surface of the cube?

A
The top surface of cube will become negatively charged

B
The front surface of tghe cube will become positively charged

C
The front surface of tghe cube will become negatively charged

D
Both top and front surface of cube will become positively charged.
Question 4
1 / -0

The number of minority carriers crossing the junction of a diode depends primarily on the :

A
concentration of doping impurities

B
magnitude of potential barrier

C
magnitude of the forward bias voltage

D
rate of thermal generation of electron-hole pair

Solution

The minority carriers in a diode are the ‘Holes’ and ‘Free Electrons’ for the $${\text{p - }}$$side and $${\text{n - }}$$side, respectively. The minority charge carrier’s movement depends on the thermal generation rate at the junction inside the diode. Which further depends on the rate of thermal generation of electron-hole pair.
So, the correct option is (D)
Question 5
1 / -0

The logic operation carried out by the circuit below is that of

A
AND gate

B
OR gate

C
NOT gate

D
NAND gate

Solution
Question 6
1 / -0

Current flowing in a Zener diode as shown in circuit: (Given diode is an ideal and $$V_z = 4V$$)

A
$$0.4$$ A

B
$$0.5$$ A

C
$$0.9$$ A

D
$$0.1$$ A

Solution
Question 7
1 / -0

The given truth table is
A B Y
0 0 0
1 0 1
0 1 1
1 1 0

A
XOR gate

B
NAND gate

C
OR gate

D
AND gate

Solution
Question 8
1 / -0

What is the voltage across an ideal p-n junction diode for shown circuit?

A
0.7 V

B
1 V

C
2 V

D
None of these

Solution

As the diode is connected in reverse bias in the circuit, the circuit will act like an open circuit. Hence, the voltage across the circuit will not change. It will remain $${\text{2 Volt}}$$.
So, option (C) is correct.
Question 9
1 / -0

The combination of gates shown in the circuit is equivalent to

A
OR

B
AND

C
NAND

D
NOR
Question 10
1 / -0

The charge in emitter current of a PNP transistor is 'x' and the corresponding change in the base current is 'y'. The $$\beta$$ factor of the transistor is

A
$$\dfrac{x}{y}$$

B
$$\dfrac{x-y}{x}$$

C
$$\dfrac{x-y}{y}$$

D
$$\dfrac{x+y}{y}$$

Solution

We have,
$$\beta = \left( {\frac{{\Delta {I_C}}}{{\Delta {I_B}}}} \right) = \left( {\frac{{\Delta {I_E} - \Delta {I_B}}}{{\Delta {I_B}}}} \right) = \frac{{x - y}}{y}$$