NCERT Class XII Chapter
Semiconductor Electronics
Questions With Solutions
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Question : 19
Total: 19
Write the truth table for the circuits given in figure consisting of NOR gates only. Identify the logic operations (OR, AND, NOT) performed by the two circuits.
Solution:
Boolean expression for logic circuit (a)
Here the given NOR gate with short circuit input is acting as NOT gate.
Its truth table is
Boolean expression for logic circuit (b)
So, output by De-Morgan’s theorem, Y =
.
Hence, the logic circuit acts like AND gate.
Its truth table is
Here the given NOR gate with short circuit input is acting as NOT gate.
Its truth table is
| A | Y |
|---|---|
| 0 | 1 |
| 1 | 0 |
Boolean expression for logic circuit (b)
So, output by De-Morgan’s theorem, Y =
Hence, the logic circuit acts like AND gate.
Its truth table is
| A | B | Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
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