## Logic Gates and Boolean Algebra Questions and Answers

### Q1. What is Boolean Algebra?

Boolean algebra is a mathematic system of logic in which truth functions are expresses as symbols and then these symbols are manipulated to arrive at conclusion.

### Q2. What are the basic logic elements?

Basic logic elements are NOT gate, AND gate, OR gate and the flip-flop.

### Q3. What is a truth table?

Truth table is a table that gives outputs for all possible combinations of inputs to a logic circuit.

### Q4. Define positive logic and negative logic.

If the higher of the two voltages represents a 1 and the lower voltage represents a 0, then the logic is called a positive logic. On the other hand, if the lower voltage represents a 1 and the higher voltage a 0, we have a negative logic.

### Q5. What is pulse logic system?

A logic system in which a bit is recognized by the presence or absence of a pulse is called a pulse or dynamic logic system.

### Q6. What is an inverter?

An inverter is a logic gate whose output is the inverse or complement of its input.

### Q7. What are the universal logic gates?

Universal gate is a gate that can perform all the basic logical operations such as NAND and NOR gates.

### Q8. What is the specialty of NAND and NOR gates?

The specialty of NAND and NOR gates is that they are universal gates and can perform all the basic logical operations.

### Q9. Why NAND-NAND realization is preferred over AND-OR realization?

NAND-NAND realization needs only one type of gate(NAND), that minimizes IC package counter.

### Q10. Why is a two-input NAND gate called universal gate?

NAND gate is called universal gate because any digital system can be implemented with the NAND gate. Sequential and combinational circuits can be constructed with these gates because element circuits like flip-flop can be constructed from two NAND gates connected back-to-back. NAND gates are common in hardware because they are easily available in the ICs form. A NAND gate is in fact a NOT-AND gate. It can be obtained by connecting a NOT gate in the output of an AND gate.

### Q12. What is associate law?

Associate law is a low of addition and multiplication and according to this law grouping of the variable is the ORing or ANDing of several variables is immaterial and the results obtained are the same.