JEE MAIN - Physics (2021 - 31st August Evening Shift - No. 7)
If VA and VB are the input voltages (either 5V or 0V) and V0 is the output voltage then the two gates represented in the following circuit (A) and (B) are :-
_31st_August_Evening_Shift_en_7_2.png)
AND and OR Gate
OR and NOT Gate
NAND and NOR Gate
AND and NOT Gate
Explanation
VA = 5V $$\Rightarrow$$ A = 1
VA = 0V $$\Rightarrow$$ A = 0
VB = 5V $$\Rightarrow$$ B = 1
VB = 0V $$\Rightarrow$$ B = 0
If A = B = 0, there is no potential anywhere here V0 = 0
If A = 1, B = 0, Diode D1 is forward biased, here V0 = 5V
If A = 0, B = 1, Diode D2 is forward biased hence V0 = 5V
If A = 1, B = 1, Both diodes are forward biased hence V0 = 5V
Truth table for Ist_31st_August_Evening_Shift_en_7_3.png)
$$\therefore$$ Given circuit is OR gate
For IInd circuit
VB = 5V, A = 1
VB = 0V, A = 0
When A = 0, E - B junction is unbiased there is no current through it
$$\therefore$$ V0 = 1
When A = 1, E-B junction is forward biased
V0 = 0
$$\therefore$$ Hence this circuit is NOT gate
VA = 0V $$\Rightarrow$$ A = 0
VB = 5V $$\Rightarrow$$ B = 1
VB = 0V $$\Rightarrow$$ B = 0
If A = B = 0, there is no potential anywhere here V0 = 0
If A = 1, B = 0, Diode D1 is forward biased, here V0 = 5V
If A = 0, B = 1, Diode D2 is forward biased hence V0 = 5V
If A = 1, B = 1, Both diodes are forward biased hence V0 = 5V
Truth table for Ist
$$\therefore$$ Given circuit is OR gate
For IInd circuit
VB = 5V, A = 1
VB = 0V, A = 0
When A = 0, E - B junction is unbiased there is no current through it
$$\therefore$$ V0 = 1
When A = 1, E-B junction is forward biased
V0 = 0
$$\therefore$$ Hence this circuit is NOT gate
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