Electronics and Communication Engineering - Digital Electronics

36. 

Which display device resembles vacuum tube?

A. LED
B. LCD
C. VF
D. None of these

Answer: Option C

Explanation:

It is similar to triode.


37. 

The number of inputs and outputs of a full adder are

A. 3 and 2 respectively
B. 2 and 3 respectively
C. 4 and 2 respectively
D. 2 and 4 respectively

Answer: Option A

Explanation:

Inputs are carry from lower bits and two other bits. Outputs are SUM and CARRY.


38. 

A VF display operates on the principle of a vacuum diode.

A. True
B. False

Answer: Option B

Explanation:

It operates on the principle of vacuum triode.


39. 

In a 3 input NAND gate, the number of states in which output is 0 equals

A. 8
B. 1
C. 6
D. 5

Answer: Option B

Explanation:

Only one input, i.e., A = 1, B = 1 and C = 1 gives low output.


40. 

In a mod-12 counter the input clock frequency is 10 kHz. The output frequency is

A. 0.833 kHz
B. 1.0 kHz
C. 0.91 kHz
D. 0.77 kHz

Answer: Option A

Explanation:

Mod-12 counter is divide by 12 counter. Output frequency = = 0.833 kHz.