JEE (Main) · Physics, Class 12
Electronic Devices: JEE Main PYQ, 2020–2025
Electronic Devices (Physics, Class 12) has been asked 135 times in the 111 JEE (Main) shift papers from 2020–2025: about 1.2 questions a paper, 4% of all Physics questions. It is the 12th most-asked of 20 Physics chapters. The 2025 shifts had 15 from it in all. Last checked 28 October 2026.
Questions per year, all shifts
Year by year.
| Year | Questions |
|---|---|
| 2020 | 14in 14 papers |
| 2021 | 43in 26 papers |
| 2022 | 30in 24 papers |
| 2023 | 14in 12 papers |
| 2024 | 19in 18 papers |
| 2025 | 15in 17 papers |
JEE (Main) is sat in many shifts a year, each with its own paper; the counts add up every shift. 2021–2024 papers had 30 questions a subject, the others 25.
Inside the chapter
Topics asked most.
- Logic gates47
- Special-purpose diodes34
- Semiconductors27
- p-n junction diode24
- Rectifiers3
Try it
10 Electronic Devices questions to practise.
Our own questions, written in the JEE Main pattern and checked, each with an explanation. Pick an option to see the answer.
Q1 · Physics · Electronic Devices
A solar cell is illuminated and connected to a load. In which direction does the photo-generated current flow through the external circuit?
Answer: (B)
A solar cell is a p-n junction with no external bias. Light generates electron-hole pairs near the junction. The built-in electric field separates them, pushing electrons to the n-side and holes to the p-side. Conventional current therefore flows out of the p-side, through the external load, and back into the n-side.
Q2 · Physics · Electronic Devices
A capacitor is connected in parallel with the load resistor R at the output of a half-wave rectifier to smooth the pulsating output. Which single change would REDUCE the ripple in the output voltage, with everything else unchanged?
Answer: (D)
The capacitor charges to the peak voltage while the diode conducts, then discharges through R while the diode is off. The fall in voltage between peaks depends on how small the discharge time is compared with RC. A larger RC means a smaller fall, hence less ripple. Increasing C does this. Decreasing R, decreasing C or lowering the frequency (longer discharge time) all make the ripple worse.
Q3 · Physics · Electronic Devices
A silicon crystal is doped with phosphorus (Group 15) and kept at room temperature, with all the donor atoms ionised. Which statement about the charge on the crystal is correct?
Answer: (A)
Doping changes the number of mobile carriers, not the net charge. Phosphorus atoms are neutral before incorporation. Each uses four of its five valence electrons in bonds, and the fifth is loosely bound. When this electron is freed, it leaves behind a fixed P⁺ ion in the lattice. The free electrons (negative) are therefore balanced by the P⁺ ions (positive) plus the few holes, so the crystal remains neutral. The option claiming a net charge ignores one of the two partners created by ionisation. The option relying on nₑ = nₕ applies a rule valid only for intrinsic material.
Q4 · Physics · Electronic Devices
An ideal diode is connected in series with a load resistor and an AC source, forming a half-wave rectifier. During the negative half-cycle of the input, what is the voltage across the load resistor?
Answer: (A)
A junction diode conducts only when it is forward-biased. In the negative half-cycle, the diode is reverse-biased and, ideally, carries no current. With no current through the load resistor, the voltage across it is zero. This is why the rectified output has no negative half-cycles.
Q5 · Physics · Electronic Devices
The same three inputs A, B, C are applied to a three-input NAND gate and to a three-input NOR gate. For how many of the eight possible input combinations (A, B, C) does the NAND gate give output 1 while the NOR gate gives output 0?
Answer: (A)
A three-input NAND output is 0 only when all inputs are 1, so it is 1 for 7 combinations (all except 111). A three-input NOR output is 1 only when all inputs are 0, so it is 0 for 7 combinations (all except 000). The combinations satisfying both conditions are all eight minus 000 and 111, which is 6.
Q6 · Physics · Electronic Devices
In the circuit described, a 9.7 V battery is joined in series with a 1 kΩ resistor. The other end of this resistor feeds two branches connected in parallel. Branch A is a silicon diode (drop 0.7 V when conducting) connected in forward bias in series with a 2 kΩ resistor. Branch B is an identical silicon diode connected in reverse bias in series with a 2 kΩ resistor. Both branches return to the battery. The current drawn from the battery is:
Answer: (A)
A diode conducts only when forward biased. Branch B is reverse biased, so it carries essentially no current and can be removed. The circuit is then the battery, the 1 kΩ resistor, the forward silicon diode (0.7 V drop) and the 2 kΩ resistor in series. I = (9.7 − 0.7) V / (3 kΩ) = 3.0 mA.
Q7 · Physics · Electronic Devices
A two-input XOR (exclusive-OR) gate receives A = 1 and B = 1. What is its output Y?
Answer: (B)
An XOR gate's output is 1 when its two inputs differ and 0 when they are equal. Here A = B = 1, so the inputs are equal and Y = 0. Remember this as: XOR = 1 only for unequal inputs.
Q8 · Physics · Electronic Devices
What is the minimum number of two-input NAND gates needed to construct one two-input AND gate?
Answer: (A)
AND = NOT(NAND). The first NAND gate gives NOT(A·B). A NAND gate with both inputs joined acts as a NOT gate, since NOT(X·X) = NOT X. Feeding the first output to this second NAND gives NOT(NOT(A·B)) = A·B. So 2 gates are sufficient, and one gate alone cannot give AND.
Q9 · Physics · Electronic Devices
A silicon p-n junction diode is reverse biased at a voltage well below its breakdown voltage. First the reverse voltage is increased from 2 V to 6 V at a fixed temperature of 300 K. Then, with the reverse voltage held at 6 V, the temperature is raised to 350 K. Which row correctly describes the depletion region width and the reverse current in the two steps?
Answer: (A)
In reverse bias the applied voltage adds to the barrier, so the depletion region widens (step 1). The only current is the small drift current of minority carriers swept across the junction. At a given temperature all the minority carriers generated near the junction are already collected, so this current saturates and barely changes with voltage (reverse saturation current). The minority carrier concentration comes from thermal generation of electron-hole pairs, which rises rapidly with temperature, so heating to 350 K increases the reverse current appreciably (step 2). Hence the width increases, the current is nearly constant with voltage, and it increases with temperature.
Q10 · Physics · Electronic Devices
A silicon crystal is doped with a trivalent impurity to form a p-type semiconductor. Which charge carriers are the majority carriers in this material?
Answer: (A)
Doping with a trivalent impurity gives one fewer valence electron per dopant atom than silicon, which leaves a vacancy called a hole. In p-type material holes outnumber electrons, so holes are the majority carriers and electrons are the minority carriers.
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All 135 real JEE Main questions from Electronic Devices.
The questions from the actual papers, with the official answer and an explanation for each — chapter by chapter, or as full timed papers.
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About Electronic Devices in JEE Main.
How many questions come from Electronic Devices in JEE Main?
Electronic Devices (Physics, Class 12) has been asked 135 times in the 111 JEE (Main) shift papers from 2020–2025: about 1.2 questions a paper, 4% of all Physics questions. It is the 12th most-asked of 20 Physics chapters. The 2025 shifts had 15 from it in all.
Which topics of Electronic Devices are asked most in JEE Main?
Logic gates (47), Special-purpose diodes (34), Semiconductors (27), p-n junction diode (24), counted over the papers from 2020–2025.
Is Electronic Devices important for JEE Main 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 12 of 20 in Physics; use that to decide how much time it gets, not whether to study it.
Where can I solve Electronic Devices JEE Main previous year questions?
On Nikaalle, free: sign up and practise every past JEE Main question from Electronic Devices with an explanation for each, or sit the full papers timed. The ten questions on this page are our own, written in the same pattern.
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