Digital electronics MCQ For BAC Students

 

Q1. The energy gap in a semiconductor is typically of the order of:

a) 10 eV

b) 5 eV

c) 1 eV ✅

d) 0.01 eV

Q2. A PN junction acts as a:

a) Rectifier ✅

b) Amplifier

c) Oscillator

d) Filter

Q3. In forward bias, the width of the depletion region:

a) Increases

b) Decreases ✅

c) Remains constant

d) Becomes zero

Q4. In reverse bias, the current through a PN junction is mainly due to:

a) Majority carriers

b) Minority carriers ✅

c) Both

d) None

Q5. A transistor can be used as a:

a) Switch ✅

b) Resistor

c) Capacitor

d) Diode

Q6. The configuration of a transistor that provides the highest current gain is:

a) Common Base

b) Common Collector

c) Common Emitter ✅

d) None of these

Q7. TTL stands for:

a) Transistor Transistor Logic ✅

b) Transistor Tuned Logic

c) Triode Transistor Logic

d) Transient Trigger Logic

Q8. Which of the following logic families has the lowest power consumption?

a) TTL

b) ECL

c) CMOS ✅

d) RTL

Q9. In a digital circuit, a diode can act as a:

a) Amplifier

b) Switch ✅

c) Filter

d) Oscillator

Q10. In saturation region, a transistor behaves like a:

a) Closed switch ✅

b) Open switch

c) Amplifier

d) Resistor

Q11. The output of an AND gate is 1 only if:

a) All inputs are 1 ✅

b) Any input is 1

c) All inputs are 0

d) Any input is 0

Q12. The output of an OR gate is 0 only if:

a) All inputs are 1

b) All inputs are 0 ✅

c) Any input is 1

d) None

Q13. The NOT gate performs:

a) AND operation

b) OR operation

c) Inversion ✅

d) Buffering

Q14. NAND gate is a combination of:

a) AND + OR

b) AND + NOT ✅

c) OR + NOT

d) NOT + OR

Q15. The universal gates are:

a) AND, OR

b) XOR, XNOR

c) NAND, NOR ✅

d) AND, NOT

Q16. The Boolean expression for an OR gate is:

a) A·B

b) A + B ✅

c) A ⊕ B

d) Ā + B

Q17. According to DeMorgan’s theorem:

a) (AB)’ = A’ + B’ ✅

b) (A + B)’ = AB’

c) (A + B)’ = A’ + B’

d) (AB)’ = A’B

Q18. The XOR gate gives output 1 when:

a) Inputs are same

b) Inputs are different ✅

c) Both inputs 0

d) Both inputs 1

Q19. K-Map is used for:

a) Designing registers

b) Minimizing Boolean expressions ✅

c) Counting binary numbers

d) None

Q20. A 2-variable K-Map has:

a) 2 cells

b) 4 cells ✅

c) 8 cells

d) 16 cells

Q21. The simplest form of Boolean expressions is known as:

a) Canonical form

b) Standard form

c) Minimal form ✅

d) Complex form

Q22. In Sum of Products (SOP) form, variables are:

a) Added together

b) Multiplied within each term and added overall ✅

c) Subtracted

d) Divided

Q23. A combinational circuit has output depending on:

a) Present input only ✅

b) Past input

c) Clock pulse

d) Feedback

Q24. Example of a combinational circuit:

a) Flip-flop

b) Counter

c) Adder ✅

d) Register

Q25. A 4-variable K-Map has how many cells?

a) 4

b) 8

c) 16 ✅

d) 32

Q26. A circuit whose output depends on both input and previous output is:

a) Combinational

b) Sequential ✅

c) Linear

d) Analog

Q27. The basic storage element in a sequential circuit is a:

a) Flip-flop ✅

b) Logic gate

c) Multiplexer

d) Encoder

Q28. The output of a Half Adder is:

a) Sum and Difference

b) Sum and Carry ✅

c) Carry and Borrow

d) Difference and Borrow

Q29. Which gate combination is used in a Half Adder?

a) AND, OR

b) AND, XOR ✅

c) OR, NOT

d) NAND, NOR

Q30. The Full Adder has how many inputs and outputs?

a) 2 inputs, 2 outputs

b) 3 inputs, 2 outputs ✅

c) 3 inputs, 1 output

d) 2 inputs, 1 output

Q31. The D flip-flop is also known as:

a) Delay flip-flop ✅

b) Data flip-flop

c) Dual flip-flop

d) None

Q32. In a JK flip-flop, when J = K = 1, the output will:

a) Set

b) Reset

c) Toggle ✅

d) Remain unchanged

Q33. A 4-bit shift register can store:

a) 2 bits

b) 4 bits ✅

c) 8 bits

d) 16 bits

Q34. A multiplexer is also known as:

a) Data selector ✅

b) Data distributor

c) Encoder

d) Decoder

Q35. An encoder performs the function of:

a) Converting binary to decimal

b) Converting information into coded form ✅

c) Converting analog to digital

d) Decoding