Which logic gate is specified by given circuit
Which logic gate is specified by given circuit
- AND
- OR
- NAND
- NOR
The Correct Option is D
Approach Solution - 1
The correct answer is (D): NOR.
| A | B | \(\lambda\) |
| 0 | 0 | 1 |
| 1 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 1 | 0 |
Approach Solution -2
Transistor Logic Gate Problem
Step 1: Analyze the Circuit
The circuit shows two NPN transistors connected in parallel, with their collectors joined and connected to the LED and resistor. The bases of the transistors are the inputs A and B.
Step 2: Transistor Behavior
An NPN transistor acts as a closed switch (conducts) when a high voltage (1) is applied to its base. It acts as an open switch (doesn’t conduct) when a low voltage (0) is applied to its base.
Step 3: LED Condition
The LED glows (output Y = 1) only when the current flows through it. This happens when the transistors are OFF (not conducting), pulling the collector voltage high.
Step 4: Truth Table
| A | B | Y |
|---|---|---|
| 0 | 0 | 1 |
| 1 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 1 | 0 |
When both A and B are 0, both transistors are OFF, and the LED glows (Y=1). If either A or B or both are 1, at least one transistor is ON, pulling the collector voltage low and turning the LED OFF (Y=0). This truth table represents a NOR gate.
Conclusion:
The logic gate equivalent to the given diagram is a NOR gate (Option 4).
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Concepts Used:
Logic Gates
AND Gate
It is the gate, where a circuit performs an AND operation. It has n number of input where (n >= 2) and one output.
OR Gate
It is the gate, where a circuit performs an OR operation. It has n number of input where (n >= 2) and one output.
NOT Gate
An inverter is also called NOT Gate. It has one input and one output where the input is A and the output is Y.
NAND Gate
A NAND operation is also called a NOT-AND operation. It has n number of input where (n >= 2) and one output.
NOR Gate
A NOR operation is also called a NOT-OR operation. It has n number of input where (n >= 2) and one output.
XOR Gate
XOR or Ex-OR gate is a specific type of gate that can be used in the half adder, full adder, and subtractor.
XNOR Gate
XNOR gate is a specific type of gate, which can be used in the half adder, full adder, and subtractor. The exclusive-NOR gate is flattened as an EX-NOR gate or sometimes as an X-NOR gate. It has n number of input (n >= 2) and one output.