Semiconductor Electronics

A full wave rectifier circuit consists of two p-n junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components removes the ac ripple from the rectified output?

1. p-n junction diodes
2. Capacitor
3. Load resistance
4. A centre-tapped transformer

For the following logic circuit, the truth table is: [figure]

1. [figure]
2. [figure]
3. [figure]
4. [figure]

[figure] In the given circuits (a), (b) and (c), the potential drop across the two p-n junctions are equal in

1. Circuit (a) only
2. Circuit (b) only
3. Circuit (c) only
4. Both circuits (a) and (c)

In half wave rectification, if the input frequency is 60 Hz, then the output frequency would be

1. Zero
2. 30 Hz
3. 60 Hz
4. 120 Hz

[figure] The truth table for the given logic circuit is

1. [figure]
2. [figure]
3. [figure]
4. [figure]

[figure] Identify the equivalent logic gate represented by the given circuit

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

The incorrect statement about the property of a Zener diode is :

1. p and n regions of Zener diode are heavily doped
2. Zener voltage remains constant at breakdown
3. It is designed to operate under reverse bias
4. Depletion region formed is very wide

The collector current in a common base amplifier using n-p-n transistor is 24 mA. If 80% of the electrons released by the emitter is accepted by the collector, then the base current is numerically :

1. 3 mA and entering the base
2. 6 mA and leaving the base
3. 3 mA and leaving the base
4. 6 mA and entering the base

Consider the following statements (A) and (B) and identify the correct answer. (A) A Zener diode is connected in reverse bias, when used as a voltage regulator. (B) The potential barrier of p-n junction lies between 0.1 V to 0.3 V.

1. (A) is incorrect but (B) is correct.
2. (A) and (B) both are correct.
3. (A) and (B) both are incorrect.
4. (A) is correct and (B) is incorrect.

The electron concentration in an n-type semiconductor is the same as hole concentration in a p-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them.

1. No current will flow in p-type, current will only flow in n-type
2. Current in n-type = current in p-type
3. current in p-type > current in n-type
4. current in n-type > current in p-type