Logic Gates

Q.

Why logic gates are used?

Q. Name the gate represented by the following circuit.

1. $\text{OR gate}$
2. $\text{XOR gate}$
3. $\text{AND gate}$
4. $\text{NAND gate}$

Q.

Where are logic gates used?

Q.

A gate has the following truth table

P 1 1 0 0

Q 1 0 1 0

R 1 0 0 0

The gate is

1. NOR

2. OR

3. NAND

4. AND

Q.

For the circuits shown below, the Boolean polynomial is

1. $\left(~p\vee q\right)\vee \left(p\vee ~q\right)$

2. $\left(~p\wedge p\right)\wedge \left(q\wedge ~q\right)$

3. $\left(~p\wedge ~q\right)\wedge \left(q\wedge p\right)$

4. $\left(~p\wedge q\right)\vee \left(p\wedge ~q\right)$

Q. How many NAND gates are used in an OR gate?

1. Four
2. Two
3. Three
4. Five

Q.

Boolean algebra is essentially based on ?

1. Truth

2. Logic

3. Symbol

4. Numbers

Q. As the switch $S$ is closed in the circuit shown in figure, current passing through it will be

1. $25/8\text{A}$
2. $8/25\text{A}$
3. $4.5\text{A}$
4. $6.0\text{A}$

Q. In the circuit as shown in figure, A and B represent two inputs and C represents the

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

Q. NOT gates are used to reverse the input signal.

1. False
2. True

Q. The output of a XOR gate is high when

1. both the inputs are high
2. both the inputs are low
3. one input is high while another is low
4. None of these

Q. The correct Boolean operation represented by the circuit diagram drawn is

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

Q. To get an output Y = 1 from the circuit shown in figure the inputs A, B and C must be respectively

1. 1, 0, 1
2. 1, 1, 0
3. 0, 1, 0
4. 1, 0, 0

Q.

Which represents NAND gate

1. 

2. 

3. 

4. 

Q. Figure shows a combination of logic gates. To what single gate is this combination equivalent?

1. $\text{XNOR}$
2. $\text{NOR}$
3. $\text{XOR}$
4. $\text{NOR}$

Q.

A logic gate is an electronic circuit which

1. Makes logic decisions

2. Allows electrons flow only in one direction

3. Works binary algebra

4. Alternates between 0 and 1 values

Q.

The logic circuit below has the input waveforms A and B as shown. Pick out the correct output waveform.

1. 

2. 

3. 

4. 

Q.
If A = 1 and B = 0, then find X and Y.

1. X = 0, Y = 1
2. X = 1, Y = 1
3. X = 0, Y =0
4. X = 1, Y = 0

Q. The correct truth table for the following logic circuit is:

1. $\begin{array}{ccc}A& B& Y\\ 0& 0& 0\\ 0& 1& 1\\ 1& 0& 0\\ 1& 1& 1\end{array}$
2. $\begin{array}{ccc}A& B& Y\\ 0& 0& 0\\ 0& 1& 1\\ 1& 0& 1\\ 1& 1& 0\end{array}$
3. 
   $\begin{array}{ccc}A& B& Y\\ 0& 0& 1\\ 0& 1& 0\\ 1& 0& 1\\ 1& 1& 0\end{array}$
4. $\begin{array}{ccc}A& B& Y\\ 0& 0& 1\\ 0& 1& 0\\ 1& 0& 0\\ 1& 1& 1\end{array}$

Q. The boolean expression for output $Y$ of a system shown in the figure will be :

1. $(\overline{A}+\overline{B})(A+B)$
2. $A.\overline{B}+\overline{A}.B$
3. $\overline{A}.\overline{B}+A.B$
4. $A.B+(\overline{A}+\overline{B})$

Q. Identify the logic operation carried out by the following circuit.

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

Q. To get an output Y = 1 from the circuit shown in figure the inputs A, B and C must be respectively

1. 1, 0, 1
2. 1, 1, 0
3. 0, 1, 0
4. 1, 0, 0