Conceptual Questions b. Write down the Boolean expression for AND, OR and NOT gate.

[2]
1. c. How is a NOT gate different from AND or OR gate? Can NOT gate be made
a. A diode can be used as a rectifier. What from junction diodes? [2]
characteristic of a diode is used in d. The output of two-input AND gate is fed to a NOT gate. Give its logic
rectification? [1] symbol and write down its truth table. Identify the new logic gate
b. Draw a circuit diagram of central tap full formed.[3]
wave rectifier. [1] 9. A logical symbol of combination of logic gates is shown in the figure.
c. A NOR gate ‘opens’ and gives an output only a. Identify the logic gate and draw its equivalent
if both inputs are ‘low’, but an OR gate ‘closes’. An AND gate ‘opens’ logic symbol. [2]
only if both inputs are ‘high’, but a NAND gate ‘closes’. b. Draw a truth table showing the output of 𝐴̅, 𝐵̅
i. Construct a truth table for the circuit shown alongside including and Y. [3]
the states at E, F and G. [3] 10.
2.
a. What is Zener diode? [1]
a. Explain the characteristics of diode. [3]
b. What is the necessity of reverse biasing in Zener diode? [1]
b. Prove NAND gate as universal gate [2]
c. Draw a circuit diagram for the use of Zener diode as voltage regulator?
3.
Describe its working. [3]
a. Sketch the symbol of a p-n junction diode and indicate the polarity of
11. A logical symbol of combination of logic gates is
its ends. [1]
shown in the figure.
b. Copy the outline of a diode bridge
a. Identify logic gates X and Y in the figure.[2]
rectifier and complete it by adding
b. Draw a truth table showing the output of X, Y
diodes in the gaps. [2]
and final output Z. [3]
c. Explain what will happen if one of the
12. A logical symbol of a logic gate is shown in
four diodes is damaged so that it stops the figure.
conducting totally in any direction. a. Identify the logic gate and draw its
Sketch a graph to show how the pd equivalent logic symbol. [2]
across the Load RL would vary with time b. Draw a truth table showing the output of
in this situation. [2] A' , B' , Y' and Y. [3]
13.
4. The circuit for full-wave rectifier is shown in
a. What is rectification? [1]
fig. A resistor R L is connected across output AB
b. Explain rectifier circuit operation with two diodes. [3]
a. Which diode conduct when S1 is positive with
c. What happens when one of the diodes becomes functionless? [1]
respect to S2? [1]
Give reasons/ answers
b. What is the direction of current across R L ? [1]
c. Sketch the graph showing nature of input 1. Why is a NOT gate called an inverter?
signal, output signal and filtered output signal. [3] 2. Why is semiconductor damaged by strong current?
5. 3. Distinguish between ordinary diode and Zener diode.
Numerical
a. Define depletion layer and barrier potential. [2]
1. When the voltage drop across p-n junction diode is increased from 0.65
b. Explain the working of a PN junction diode in forward and reversed V to 0.70 V, the change in the diode current is 5 mA. What is dynamic
biased. [3] resistance of diode? [Ans :- 10 Ω]
c. Discuss the function of Zener diode as a voltage regulator. [3] 2. A p-n junction diode is forward biased and connected to a series resistor
6. of 100 Ω, and 4.5 V d.c. battery. The barrier potential at the junction is
a. Define knee voltage and breakdown voltage. [2] 0.5 V. Find the current in the circuit. [Ans :- 40 mA]
b. Explain the biasing characteristics of a junction diode. [3] 3. Calculate the values of output
c. Discuss the application of p-n junction diode as full wave rectifier. [3] voltage, Current (I) and load
7. current (IL) from the given circuit
a. The PN junction diode allows only the unidirectional flow of current. diagram.
Explain the detailed mechanism with necessary diagrams. [3] [Ans :- I = 5A, IL = 4.167A]

b. Give the logic symbol and truth table of NOR gate. [2]
8.
a. What is a logic gate? [1]