Semiconductor Electronics · Question 52

In an unbiased p-n junction, holes diffuse from the p-region to n-region because of

1. The attraction of free electrons of n-region.
2. The higher hole concentration in p-region than that in n-region.
3. The higher concentration of electrons in the n-region than that in the p-region.
4. The potential difference across the p-n junction.

One way in which the operation of an n-p-n transistor differs from that of a p-n-p is

1. The emitter junction injects minority carriers into the base region of the p-n-p
2. The emitter injects holes into the base of the p-n-p and electrons into the base region of n-p-n
3. The emitter injects holes into the base of n-p-n
4. The emitter junction is reverse biased in n-p-n

To get an output Y = 1 in given circuit which of the following input will be correct ? [figure]

1. A 1, B 0, C 0
2. A 1, B 0, C 1
3. A 1, B 1, C 0
4. A 0, B 1, C 0

The input resistance of a silicon transistor is 100 . Base current is changed by 40 which results in a change in collector current by 2 mA. This transistor is used as a common emitter amplifier with a load resistance of 4 k . The voltage gain of the amplifier is

1. 2000
2. 3000
3. 4000
4. 1000

Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is [figure]

1. 0.75 A
2. zero
3. 0.25 A
4. 0.5 A

C and Si both have same lattice structure; having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor. This is because

1. In case of C the valence band is not completely filled at absolute zero temperature.
2. In case of C the conduction band is partly filled even at absolute zero temperature.
3. The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third.
4. The four bonding electrons in the case of C lie in the third orbit, whereas for Si they lie in the fourth orbit.

The figure shows a logic circuit with two inputs A and B and the output C. The voltage wave forms across A, B and C are as given. The logic circuit gate is [figure]

1. OR gate
2. NOR gate
3. AND gate
4. NAND gate

In a CE transistor amplifier, the audio signal voltage across the collector resistance of 2 k is 2 V. If the base resistance is 1 k and the current amplification of the transistor is 100, the input signal voltage is

1. 0.1 V
2. 1.0 V
3. 1 mV
4. 10 mV

Transfer characteristics [output voltage (V0) vs input voltage (Vi)] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used [figure]

1. in region III
2. both in region (I) and (III)
3. in region II
4. in region I

A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is [figure]

1. 5 mA
2. 10 mA
3. 15 mA
4. 20 mA