Physics Class 12 NCERT Solutions: Chapter 14 Semiconductor Electronics Materials Devices and Simple Circuits Part 4

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Basic Logic Gates

Basic Logic Gates

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Q: 15. You are given the two circuits as shown in figure. Show that circuit (a) acts as OR gate while the circuit (B) acts as AND gate.

Q 15 Circuit of OR Gate and AND Gate

Q 15 Circuit of or Gate and and Gate

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(A) A and B are the inputs and is the output of the given circuit. The left half of the given figure acts as the NOR Gate, while the right half acts as the NOT Gate. This is shown in the following figure.

Q 15 A CIrcuit of Half-NOR Gate ang Half NOT Gate

Q 15 a CIrcuit of Half-Nor Gate Ang Half NOT Gate

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Hence, the output of the NOR Gate

This will be the input for the Not Gate. Its output will be

Hence, this circuit functions as an OR Gate.

(B) A and B are the inputs and Y is the output of the given circuit. It can be observed from the following figure that the input that the inputs of the right half NOR Gate are the outputs of the two NOT Gates.

Q 15 B Circuit of theRightHalfNORGatearethe Outputsofthe

Q 15 B Circuit of theRightHalfNORGatearethe Outputsofthe

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Hence, the output of the given circuit can be written as:

Hence, this circuit functions as an AND Gate.

Q: 16. Write the truth table for a NAND gate connected as given in Figure.

Q 16 Circuit of The NAND Gate

Q 16 Circuit of the NAND Gate

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Hence identify the exact logic operation carried out by this circuit.

Answer:

A acts as the two inputs of the NAND gate and Y is the output, as shown in the following figure.

Q 16 1 Circuit of The NAND Gate

Q 16 1 Circuit of the NAND Gate

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The truth table for equation (i) can be drawn as:

Q_16_2_Truth Table for NAND Gate

A

0

1

This circuit functions as a NOT gate. The symbol for this logic circuit is shown as:

Q 16 3 Circuit of the NOT Gate

Q 16 3 Circuit of the NOT Gate

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Q: 17. You are given two circuits as shown in figure, which consist of NAND gates. Identify the logic operation carried out by the two circuits.

Q 17 Image of NAND Gate for Identify the Logic Operation of …

Q 17 NAND Gate for Identify the Logic Operation of the 2 Cir …

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Answer:

In both the given circuits, A and B are the inputs and Y is the output.

(A) The output of the left NAND gate will be. As shown in the following figure.

Q 17 A The Output of the Combination of the Two NAND Gates

Q 17 a the Output of the Combination of the Two NAND Gates

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Hence, the output of the combination of the two NAND gates is given as:

Hence, this circuit functions as an AND gate.

(B) is the output of the upper left of the NAND gate and is the output of the lower half of the NAND gate, as shown in the following figure.

Q 17 B The Output of the Upper Left of the NAND gate and Low …

Q 17 B Output of Upper Left and Lower Half of the NAND Gate

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Hence, the output of the combination of the NAND gates will be given as:

Hence, this circuit functions as an OR gate.