Question

: In negative logic, the logic state 1 corresponds to
A. Negative voltage
B. Zero voltage
C. More negative voltage
D. Lower voltage level
E. None of the above

Answer 1

Recall the basics of a digital circuit in which different logic gates are used. Go through the meaning of the logic inputs 0 and 1 to the digital circuit. Then recall the working of a negative logic circuit and hence, determine that for the input 1 to a negative logic circuit, what is the output and what is the meaning of this output. Hence, choose the correct option.

Complete answer:
In the present question, we have asked the meaning of logic state 1 in a negative logic system.We know that there are various digital circuits used now-a-days.In a digital circuit, there are only two inputs and two outputs which are denoted by 0 and 1. Hence, these digital circuits are also known as the binary circuits.

We know that the logic state 1 in a digital circuit corresponds to the high voltage and the logic state 0 corresponds to the low voltage.The negative logic circuits are the circuits which reverse the input to its opposite value. This means that if the input is 0 then the output is 1 and if input is 1 then the output is 0.Thus, when the input to the negative logic circuit is 1 then the output must be zero.

The zero output in the digital system does not mean negative, zero or more negative voltage. The 0 output indicates that the output is lower than the input then the input may be whatever.Therefore, in negative logic, the logic state 1 corresponds to the output 1 with lower voltage level.

Hence, the correct option is D.

Note: The students may think that we have asked the meaning of the logic state 1 in a negative logic circuit. But the students should keep in mind that we have asked that if 1 is the input to the negative logic circuit then what should be the output of that negative logic circuit and what is the meaning of this output from the circuit.