Semiconductor Electronics

20 JEE Main questions · Physics

Transistors and logic

PhysicsJEE Main 21 Jan 2026, Shift 1·Q17·MCQ·Easy–moderate
Open
The given circuit works as:
1. (1)AND gate
2. (2)NOR gate
3. (3)NAND gate
4. (4)OR gate
PhysicsJEE Main 22 Jan 2026, Shift 1·Q9·MCQ·Moderate
Open
Find the correct combination of A, B, C and D inputs which can cause the LED to glow.
1. (1)0100
2. (2)0011
3. (3)1000
4. (4)1101
PhysicsJEE Main 22 Jan 2026, Shift 2·Q10·MCQ·Easy–moderate
Open
The correct truth table for the given input data of the following logic gate is :
1. (1)
  Inputs Output
  A B C D Y
  1 1 0 1 1
  0 0 1 1 0
  1 0 1 0 1
  1 1 1 1 0
2. (2)
  Inputs Output
  A B C D Y
  1 1 0 1 1
  0 0 1 1 0
  1 0 1 0 0
  1 1 1 1 1
3. (3)
  Inputs Output
  A B C D Y
  1 1 0 1 0
  0 0 1 1 0
  1 0 1 0 1
  1 1 1 1 1
4. (4)
  Inputs Output
  A B C D Y
  1 1 0 1 0
  0 0 1 1 1
  1 0 1 0 1
  1 1 1 1 1
PhysicsJEE Main 23 Jan 2026, Shift 2·Q13·MCQ·Easy–moderate
Open
For the given logic gate circuit, which of the following is the correct truth table?
1. (1)
  n m z
  0 0 1
  0 1 0
  1 1 0
  1 0 0
2. (2)
  n m z
  0 0 0
  0 1 1
  1 1 0
  1 0 1
3. (3)
  n m z
  0 0 1
  0 1 0
  1 1 1
  1 0 0
4. (4)
  n m z
  0 0 1
  0 1 1
  1 1 0
  1 0 0
PhysicsJEE Main 24 Jan 2026, Shift 2·Q14·MCQ·Easy–moderate
Open
Identify the correct truth table of the given logical circuit.
1. (1)
  A B Y
  0 0 0
  0 1 1
  1 0 1
  1 1 0
2. (2)
  A B Y
  0 0 1
  0 1 0
  1 0 1
  1 1 0
3. (3)
  A B Y
  0 0 1
  0 1 1
  1 0 1
  1 1 0
4. (4)
  A B Y
  0 0 0
  0 1 0
  1 0 1
  1 1 0
PhysicsJEE Main 28 Jan 2026, Shift 2·Q5·MCQ·Easy–moderate
Open
Two p-n junction diodes $D_1$ and $D_2$ are connected as shown in figure. A and B are input signals and C is the output. The given circuit will function as a .
1. (1)OR Gate
2. (2)NOR Gate
3. (3)NAND Gate
4. (4)AND Gate
PhysicsJEE Main 2 Apr 2026, Shift 2·Q5·MCQ·Easy–moderate
Open
If X and Y are the inputs, the given circuit works as .
1. (1)OR gate
2. (2)AND gate
3. (3)NAND gate
4. (4)NOR gate
PhysicsJEE Main 4 Apr 2026, Shift 1·Q13·MCQ·Easy–moderate
Open
Two 4 bits binary numbers, $A = 1101$ and $B = 1010$ are given in the inputs of a logic circuit shown in figure below. The output ( $Y$ ) will be :
1. (1) $Y = 1101$
2. (2) $Y = 0010$
3. (3) $Y = 0111$
4. (4) $Y = 1000$
PhysicsJEE Main 5 Apr 2026, Shift 1·Q20·MCQ·Easy–moderate
Open
For the given logic circuit, which of the following inputs combination will make both LED-1 and LED-2 to glow ?
1. (1) $A = 0,\ B = 1,\ C = 1$
2. (2) $A = 1,\ B = 0,\ C = 0$
3. (3) $A = 1,\ B = 0,\ C = 1$
4. (4) $A = 1,\ B = 1,\ C = 0$
PhysicsJEE Main 6 Apr 2026, Shift 2·Q18·MCQ·Easy–moderate
Open
Refer to the logic circuit given below. For two inputs ( $A = 1$ , $B = 1$ ) and ( $A = 0$ , $B = 1$ ), output ( $Y$ ) will be .
1. (1)1, 0 respectively
2. (2)0, 1 respectively
3. (3)0, 0 respectively
4. (4)1, 1 respectively
We corrected a printing error in the original paper
Source printed option (2) “rsepectively” and a stray fifth option “(5) 0.0” (duplicate of (3)), omitted.
PhysicsJEE Main 8 Apr 2026, Shift 2·Q20·MCQ·Easy–moderate
Open
The output $Y$ for the given inputs $A$ and $B$ to the circuit is:
1. (1)
2. (2)
3. (3)
4. (4)

p-n junction and diodes

PhysicsJEE Main 23 Jan 2026, Shift 1·Q12·MCQ·Easy–moderate
Open
The following diagram shows a Zener diode as a voltage regulator. The Zener diode is rated at $V_Z = 5$ V and the desired current in load is 5 mA. The unregulated voltage source can supply upto 25V. Considering the Zener diode can withstand four times of the load current, the value of resistor $R_S$ (shown in circuit) should be $\Omega$ .
1. (1)4000
2. (2)10
3. (3)100
4. (4)1000
Flawed question. Dropped in the source; as printed $R_S = (25-5)\,\mathrm{V}/(20+5)\,\mathrm{mA} = 800\ \Omega$ , not among the options, and no evident intended version. It is shown for completeness and is left out of practice tests.
PhysicsJEE Main 24 Jan 2026, Shift 1·Q23·Numerical·Easy–moderate
Open
A voltage regulating circuit consisting of Zener diode, having break-down voltage of 10 V and maximum power dissipation of 0.4 W, is operated at 15 V. The approximate value of protective resistance in this circuit is $\Omega$ .
PhysicsJEE Main 28 Jan 2026, Shift 1·Q10·MCQ·Easy–moderate
Open
Assuming in forward bias condition there is a voltage drop of 0.7 V across a silicon diode, the current through diode $\mathrm{D_1}$ in the circuit is mA. (Assume all diodes in the given circuit are identical)
1. (1)20.15
2. (2)11.7
3. (3)17.6
4. (4)18.8
PhysicsJEE Main 2 Apr 2026, Shift 1·Q12·MCQ·Moderate
Open
For the given circuit (shown in part (A)) the time dependent input voltage $v_{\mathrm{in}}(t)$ and corresponding output $v_o(t)$ are shown in part (B) and part (C), respectively. Identify the components that are used in the circuit between points X and Y.
1. (1)
2. (2)
3. (3)
4. (4)
PhysicsJEE Main 4 Apr 2026, Shift 1·Q17·MCQ·Easy–moderate
Open
Consider a circuit consisting of a capacitor ( $20\ \mu$ F), resistor ( $100\ \Omega$ ) and two identical diodes as shown in figure. The resistance of diode under forward biasing condition is $10\ \Omega$ . The time constant of the circuit is $\alpha\times10^{-3}$ s. The value of $\alpha$ is .
1. (1)2.2
2. (2)2.0
3. (3)2.1
4. (4)2.4
PhysicsJEE Main 4 Apr 2026, Shift 2·Q20·MCQ·Easy
Open
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: A diode under reverse-biased condition provides very small current which is nearly independent of voltage until a critical limit at which the current increases drastically.
Reason R: Below the critical voltage limit, only majority charge carriers flow which increases drastically above critical voltage.
Choose the correct answer from the options given below.
1. (1)Both A and R are true and R is the correct explanation of A.
2. (2)Both A and R are true but R is NOT the correct explanation of A.
3. (3)A is true but R is false
4. (4)A is false but R is true
PhysicsJEE Main 4 Apr 2026, Shift 2·Q21·Numerical·Easy–moderate
Open
A diode has Zener voltage of 10 V and maximum power dissipation of 0.5 W, then the minimum resistance to be used in series with this diode for safety when it is connected to a 25 V power supply is $\Omega$ .
PhysicsJEE Main 5 Apr 2026, Shift 2·Q20·MCQ·Easy–moderate
Open
In a semiconductor p-n diode, the doping concentrations on p-side and n-side are $10^{15}$ atoms/ $\mathrm{cm^3}$ and $10^{18}$ atoms/ $\mathrm{cm^3}$ , respectively. Which one of the following statements is true?
1. (1)Widths of depletion region on either side of the interface are equal
2. (2)The depletion region width is more on p-side compared to that in n-side
3. (3)The depletion region width is more on n-side compared to that in p-side
4. (4)No depletion region forms because of unequal doping concentrations on p and n-sides
We corrected a printing error in the original paper
Source printed “Which one of the following statement is true?”.
PhysicsJEE Main 6 Apr 2026, Shift 1·Q14·MCQ·Easy–moderate
Open
The maximum rated power of the LED is 2 mW and it is used in the circuit with input voltage of 5 V as shown in the figure below. The current through resistance $R_S$ is 0.5 mA.
The minimum value of the resistance of $R_S$ , to ensure that the LED is not damaged is k $\Omega$ .
1. (1)6
2. (2)2
3. (3)4
4. (4)5

Inputs				Output
A	B	C	D	Y
1	1	0	1	1
0	0	1	1	0
1	0	1	0	1
1	1	1	1	0

Inputs				Output
A	B	C	D	Y
1	1	0	1	1
0	0	1	1	0
1	0	1	0	0
1	1	1	1	1

Inputs				Output
A	B	C	D	Y
1	1	0	1	0
0	0	1	1	0
1	0	1	0	1
1	1	1	1	1

Inputs				Output
A	B	C	D	Y
1	1	0	1	0
0	0	1	1	1
1	0	1	0	1
1	1	1	1	1