NEET Semiconductor Electronics: Materials, Devices and Simple Circuits PYQ practice sheet

20 previous-year NEET Physics questions from Semiconductor Electronics: Materials, Devices and Simple Circuits, newest papers first. Semiconductor Electronics: Materials, Devices and Simple Circuits carries 23 of the Physics questions in NEET 2020 to 2026, so this is a good place to test yourself after revising the chapter. Marking: +4 correct, −1 wrong.

Practise all 20 online

1.
RE-NEET 2026
An ideal Zener diode with breakdown voltage of $-3$ V is reverse biased with a negative input voltage $V_i = -5$ V. The magnitude of voltage difference between point $B$ and $A$ is: Figure: a series circuit with a battery, a Zener diode (between $C$ and $B$ ) and a resistor $R$ (between $B$ and $A$ ).
- (A)
  $2\ \mathrm{V}$
- (B)
  $3\ \mathrm{V}$
- (C)
  $1\ \mathrm{V}$
- (D)
  $0\ \mathrm{V}$
2.
RE-NEET 2026
Three identical p-n junction diodes $D_1$ , $D_2$ , and $D_3$ are connected across a battery as shown in the figure. If the width of the depletion regions of $D_1$ , $D_2$ and $D_3$ are $W_1$ , $W_2$ and $W_3$ , respectively, then the correct option is: Figure: three parallel branches across a $5$ V battery. Branch 1: a $1\ \mathrm{k\Omega}$ resistor in series with $D_1$ (conducting direction from the battery's positive side). Branch 2: a $1\ \mathrm{k\Omega}$ resistor in series with $D_2$ , but this branch has a gap (an open point) before it reaches the right-hand rail, so no current flows. Branch 3: $D_3$ in series with a $1\ \mathrm{k\Omega}$ resistor, with $D_3$ connected in the opposite direction.
- (A)
  $W_1 > W_2 > W_3$
- (B)
  $W_3 > W_2 > W_1$
- (C)
  $W_3 = W_1 > W_2$
- (D)
  $W_2 > W_1 = W_3$
3.
NEET 2026
The current $I$ in the circuit shown below is: (All diodes are ideal and identical) Four branches are connected in parallel across a 10 V battery. Branch 1: a $4\ \Omega$ resistor in series with a diode that conducts from the battery's positive side. Branch 2: a $3\ \Omega$ resistor with a diode in the reverse direction. Branch 3: a diode in the forward direction in series with a $2\ \Omega$ resistor. Branch 4: a diode in the reverse direction in series with a $5\ \Omega$ resistor.
- (A)
  $\dfrac59\ \text{A}$
- (B)
  $\dfrac13\ \text{A}$
- (C)
  $\dfrac53\ \text{A}$
- (D)
  $\dfrac{15}{2}\ \text{A}$
4.
NEET 2026
In the circuit shown below, the voltage appearing across the diode $D$ will be of the form: An ac source $V_i$ (a sine wave) is connected in series with an ideal diode $D$ and a resistor $R$ . $V_D$ is the voltage across the diode.
- (A)
- (B)
- (C)
- (D)
5.
NEET 2026
Two statements are given below: A. When the forward bias voltage across a p-n junction diode increases above a certain threshold voltage, the diode current increases significantly. B. This current is called reverse saturation current. Choose the correct answer from the options given below:
- (A)
  Both Statements A and B are false
- (B)
  Statement A is false, but Statement B is true
- (C)
  Both Statements A and B are true
- (D)
  Statement A is true, but Statement B is false
6.
NEET 2024
A logic circuit provides the output $Y$ as per the following truth table:
$\begin{array}{c|c|c} A & B & Y\\ \hline 0 & 0 & 1\\ 0 & 1 & 0\\ 1 & 0 & 1\\ 1 & 1 & 0 \end{array}$
- (A)
  $B$
- (B)
  $A\cdot B+\bar{A}$
- (C)
  $\bar{B}$
- (D)
  $A\cdot\bar{B}+\bar{A}$
7.
NEET 2024
Consider the following statements A and B and identify the correct answer: A. For a solar-cell, the I-V characteristics lies in the IV quadrant of the given graph. B. In a reverse biased $pn$ junction diode, the current measured in ( $\mu$ A), is due to majority charge carriers. The graph shows I on the vertical axis and V on the horizontal axis, with quadrants (I) top-right, (II) top-left, (III) bottom-left and (IV) bottom-right.
- (A)
  A is incorrect but B is correct.
- (B)
  A is correct but B is incorrect.
- (C)
  Both A and B are correct.
- (D)
  Both A and B are incorrect.
8.
NEET 2024
The output ( $Y$ ) of the given logic gate is similar to the output of an/a: Input $A$ goes to both inputs of a NAND gate and input $B$ goes to both inputs of a NOR gate. The outputs of these two gates feed the two inputs of a final NOR gate whose output is $Y$ .
- (A)
  NAND gate
- (B)
  NOR gate
- (C)
  AND gate
- (D)
  OR gate
9.
NEET 2023
Given below are two statements: Statement I : Photovoltaic devices can convert optical radiation into electricity. Statement II : Zener diode is designed to operate under reverse bias in breakdown region. In the light of the above statements, choose the most appropriate answer from the options given below :
- (A)
  Statement I is incorrect but Statement II is correct.
- (B)
  Both Statement I and Statement II are correct.
- (C)
  Both Statement I and Statement II are incorrect.
- (D)
  Statement I is correct but Statement II is incorrect.
10.
NEET 2023
A full wave rectifier circuit consists of two p-n junction diodes, a centre-tapped transformer, capacitor and a load resistance. Which of these components remove the ac ripple from the rectified output?
- (A)
  Load resistance
- (B)
  A centre-tapped transformer
- (C)
  p-n junction diodes
- (D)
  Capacitor
11.
NEET 2023
For the following logic circuit, the truth table is: Circuit (described from the figure): Input $A$ passes through a NOT gate and input $B$ passes through a separate NOT gate. The outputs of the two NOT gates feed the two inputs of a NAND gate whose output is $Y$ .
- (A)
  Rows $(A,B,Y)$ : $(0,0,0),\ (0,1,0),\ (1,0,0),\ (1,1,1)$
- (B)
  Rows $(A,B,Y)$ : $(0,0,1),\ (0,1,1),\ (1,0,1),\ (1,1,0)$
- (C)
  Rows $(A,B,Y)$ : $(0,0,0),\ (0,1,1),\ (1,0,1),\ (1,1,1)$
- (D)
  Rows $(A,B,Y)$ : $(0,0,1),\ (0,1,0),\ (1,0,1),\ (1,1,0)$
12.
NEET 2022
In the given circuits (a), (b) and (c), each made of two p-n junction diodes connected in series with their polarities as shown in the figure, the potential drop across the two p-n junctions are equal in: (Figure: circuit (a) has both diodes oriented the same way, P-N followed by P-N, in series aiding; circuit (b) has the diodes in a back-to-back orientation, P-N followed by N-P; circuit (c) has both diodes oriented the same way, N-P followed by N-P, mirroring circuit (a).)
- (A)
  Both circuits (a) and (c)
- (B)
  Circuit (a) only
- (C)
  Circuit (b) only
- (D)
  Circuit (c) only
13.
NEET 2022
In half wave rectification, if the input frequency is 60 Hz, then the output frequency would be:
- (A)
  120 Hz
- (B)
  zero
- (C)
  30 Hz
- (D)
  60 Hz
14.
NEET 2022
Given below is a logic circuit built with NAND gates, with inputs A, B and output C. The truth table for the given logic circuit is:
- (A)
  A B C: 0 0 0; 0 1 1; 1 0 0; 1 1 1
- (B)
  A B C: 0 0 0; 0 1 1; 1 0 1; 1 1 0
- (C)
  A B C: 0 0 1; 0 1 0; 1 0 0; 1 1 1
- (D)
  A B C: 0 0 1; 0 1 0; 1 0 1; 1 1 0
15.
NEET 2021
The electron concentration in an n-type semiconductor is the same as hole concentration in a p-type semiconductor. An external field (electric) is applied across each of them. Compare the currents in them.
- (A)
  current in n-type > current in p-type.
- (B)
  current in p-type > current in n-type.
- (C)
  current in n-type = current in p-type.
- (D)
  No current will flow in p-type, current will only flow in n-type.
16.
NEET 2021
Consider the following statements (A) and (B) and identify the correct answer. (A) A zener diode is connected in reverse bias, when used as a voltage regulator. (B) The potential barrier of p-n junction lies between 0.1 V to 0.3 V.
- (A)
  (A) is incorrect but (B) is correct.
- (B)
  (A) and (B) both are correct.
- (C)
  (A) and (B) both are incorrect.
- (D)
  (A) is correct and (B) is incorrect.
17.
NEET 2021
For the given circuit, the input digital signals are applied at the terminals A, B and C. What would be the output at the terminal $y$ ? Figure: the input waveforms (levels 0 V or 5 V) are shown against the time instants $t_1$ to $t_6$ . A is high during $t_1$ - $t_2$ , $t_3$ - $t_4$ and $t_5$ - $t_6$ and low otherwise. B is high only during $t_2$ - $t_4$ . C is low only during $t_2$ - $t_4$ and high otherwise. In the circuit, A and B feed an AND gate; B and C feed a NAND gate; the outputs of the AND gate and the NAND gate feed an OR gate whose output is $y$ , so $y = A\cdot B + \overline{B\cdot C}$ .
- (A)
- (B)
- (C)
- (D)
18.
NEET 2020
The increase in the width of the depletion region in a p-n junction diode is due to :
- (A)
  forward bias only
- (B)
  reverse bias only
- (C)
  both forward bias and reverse bias
- (D)
  increase in forward current
19.
NEET 2020
For the logic circuit shown, the truth table is :
- (A)
  Y = 0, 0, 0, 1 for (A, B) = (0,0), (0,1), (1,0), (1,1)
- (B)
  Y = 0, 1, 1, 1 for (A, B) = (0,0), (0,1), (1,0), (1,1)
- (C)
  Y = 1, 1, 1, 0 for (A, B) = (0,0), (0,1), (1,0), (1,1)
- (D)
  Y = 1, 0, 0, 0 for (A, B) = (0,0), (0,1), (1,0), (1,1)
20.
NEET 2020
For transistor action, which of the following statements is correct?
- (A)
  Base, emitter and collector regions should have same doping concentrations.
- (B)
  Base, emitter and collector regions should have same size.
- (C)
  Both emitter junction as well as the collector junction are forward biased.
- (D)
  The base region must be very thin and lightly doped.

Answer key

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