JEE (Main) · Physics
Experimental Skills: JEE Main PYQ, 2020–2025
Experimental Skills (Physics) has been asked 47 times in the 111 JEE (Main) shift papers from 2020–2025: about 0.4 questions a paper, 2% of all Physics questions. It is the 20th most-asked of 20 Physics chapters. The 2025 shifts had 4 from it in all. Last checked 28 October 2026.
Questions per year, all shifts
Year by year.
| Year | Questions |
|---|---|
| 2020 | 6in 14 papers |
| 2021 | 10in 26 papers |
| 2022 | 12in 24 papers |
| 2023 | 1in 12 papers |
| 2024 | 14in 18 papers |
| 2025 | 4in 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.
- Vernier calipers and screw gauge36
- Electricity experiments3
- Optics experiments3
- Properties of matter experiments2
- Semiconductor experiments2
- Heat and sound experiments1
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10 Experimental Skills 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 · Experimental Skills
In a Vernier callipers of least count 0.01 cm, the main scale reads 2.4 cm and the 6th Vernier division coincides with a main-scale division. There is no zero error. What is the reading?
Answer: (D)
Reading = main-scale reading + (coinciding Vernier division × least count) = 2.4 + 6 × 0.01 = 2.46 cm.
Q2 · Physics · Experimental Skills
To find the focal length of a concave lens, it is placed in contact with a convex lens of focal length 10 cm. The combination forms a real image, and the u–v method gives its focal length as 25 cm. What is the focal length of the concave lens?
Answer: (A)
For thin lenses in contact, 1/F = 1/f1 + 1/f2. A concave lens alone cannot form a real image, so it is paired with a stronger convex lens. Here 1/f2 = 1/F − 1/f1 = 1/25 − 1/10 = (2 − 5)/50 = −3/50 cm⁻¹, so f2 = −50/3 ≈ −16.7 cm. The negative sign is consistent with a diverging lens, and the combination's focal length (25 cm) is longer than the convex lens's (10 cm).
Q3 · Physics · Experimental Skills
In an experiment to find the density of an irregular metal piece, a student weighs it with a spring balance. The weight in air is W_a = 5.00 N and the weight when fully immersed in water is W_w = 4.00 N. Each reading has an uncertainty of ±0.05 N. The density is calculated from ρ = ρ_water × W_a/(W_a − W_w), and the density of water is taken as exact. What is the maximum percentage error in the calculated density?
Answer: (A)
Since ρ = ρ_w W_a/(W_a − W_w), the maximum fractional error is Δρ/ρ = ΔW_a/W_a + Δ(W_a − W_w)/(W_a − W_w). For a difference, the absolute errors add: Δ(W_a − W_w) = 0.05 + 0.05 = 0.10 N. So Δρ/ρ = 0.05/5.00 + 0.10/1.00 = 0.01 + 0.10 = 0.11, which is 11%. The small difference of two nearly equal readings dominates the error.
Q4 · Physics · Experimental Skills
A vernier callipers has a depth gauge, a thin rod that slides out from the back of the main scale. Which measurement is this rod designed to make?
Answer: (A)
A vernier callipers has three parts for measurement. The outer jaws measure external dimensions, the internal jaws measure internal dimensions, and the depth rod at the back of the sliding frame measures the depth of a hole or step. Because the rod moves with the sliding scale, its reading is taken in the same way as an external length. Students often mix up the internal jaws and the depth rod, since both are small and located near the top or back of the instrument.
Q5 · Physics · Experimental Skills
In the laboratory, the forward I–V characteristic of a silicon junction diode was plotted with a milliammeter in series with the diode. The same diode is now to be used for its reverse characteristic, at voltages well below breakdown. Which change to the set-up is appropriate?
Answer: (A)
A p–n junction is reverse biased when the p-side is joined to the negative terminal of the battery, so the diode connections must be reversed. Below breakdown, only minority carriers cross the junction, so the reverse current is of the order of microamperes (far smaller than the forward milliampere currents). A microammeter is therefore needed to measure it. Keeping the milliammeter, or making it less sensitive with a shunt, would give almost no reading, and leaving the polarity unchanged does not give reverse bias at all.
Q6 · Physics · Experimental Skills
In a resonance tube experiment (air column closed at one end), a tuning fork of frequency f = 500 ± 5 Hz is used. The first and second resonances are found at air-column lengths L1 = 17.0 cm and L2 = 51.0 cm, and each length has an uncertainty of ±0.1 cm. The speed of sound is calculated from v = 2f(L2 − L1), so the unknown end correction cancels. What is the speed of sound with its maximum possible absolute error?
Answer: (A)
Principle: for successive resonances in a closed pipe, L2 − L1 = λ/2, so v = fλ = 2f(L2 − L1). The end correction cancels in the difference. In the maximum-error method, the fractional errors of the factors in a product are added, and the absolute errors of quantities that are subtracted are added. Apply this here. L2 − L1 = 34.0 cm, so v = 2 × 500 × 0.340 = 340 m/s. Δ(L2 − L1) = 0.1 + 0.1 = 0.2 cm, so its fractional error is 0.2/34.0 = 0.588%. The frequency error is 5/500 = 1%. The total fractional error is 1.588%, so Δv = 340 × 0.01588 ≈ 5.4 m/s. The result is v = 340 ± 5.4 m/s.
Q7 · Physics · Experimental Skills
In a Kundt's tube experiment, fine dust settles into heaps at the nodes of the standing wave in the air column. The distance between adjacent heaps is measured as 4.0 cm when the tube is driven at 4000 Hz. What is the speed of sound in air given by these readings?
Answer: (B)
In a Kundt's tube the dust collects at displacement nodes, where the air is still. Consecutive nodes are separated by half a wavelength, so λ = 2d. Convert the spacing to SI units first (0.040 m gives λ = 0.080 m), then use v = fλ. The answer is 4000 × 0.080 = 320 m/s, which is close to the accepted value for air at about 20 °C.
Q8 · Physics · Experimental Skills
The wall thickness of a hollow metal cylinder is found as t = (D − d)/2, where D is the outer diameter and d the inner diameter. Both are measured with a vernier callipers of least count 0.01 cm, giving D = 3.46 cm and d = 2.88 cm. Taking the uncertainty in each diameter as one least count, which result gives t with its maximum absolute error?
Answer: (A)
The difference is D − d = 3.46 − 2.88 = 0.58 cm. For a difference, the maximum absolute errors add: Δ(D − d) = 0.01 + 0.01 = 0.02 cm. The thickness is half of this, so t = 0.29 cm and Δt = 0.02/2 = 0.01 cm. The result is (0.29 ± 0.01) cm.
Q9 · Physics · Experimental Skills
In an experiment to find the coefficient of viscosity of glycerine, a steel ball of diameter 4.0 mm (density 8000 kg m⁻³) falls through a tall jar of glycerine (density 1260 kg m⁻³). It covers 0.50 m at terminal velocity in 12.5 s. Taking g = 9.8 m s⁻² and using Stokes' law, what is the coefficient of viscosity of glycerine?
Answer: (D)
At terminal velocity, weight = buoyancy + viscous drag. This gives (4/3)πr³(ρ−σ)g = 6πηrv, so η = 2r²(ρ−σ)g/(9v). The radius is r = 2.0 mm = 2.0×10⁻³ m, so r² = 4.0×10⁻⁶ m². The speed is v = 0.50/12.5 = 0.040 m/s. The density difference is ρ − σ = 8000 − 1260 = 6740 kg m⁻³. Then η = 2 × 4.0×10⁻⁶ × 6740 × 9.8 / (9 × 0.040) = 0.5284/0.36 ≈ 1.47 Pa s.
Q10 · Physics · Experimental Skills
In a half-wave rectifier fed by an alternating supply and a single p-n junction diode with a load resistor, what is the output during the negative half-cycles of the input?
Answer: (A)
A diode conducts only when forward biased. In a half-wave rectifier, the positive half-cycles forward bias the diode and pass through to the load, while the negative half-cycles reverse bias it. Since almost no current flows during these, the output is zero for those intervals.
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All 47 real JEE Main questions from Experimental Skills.
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 Experimental Skills in JEE Main.
How many questions come from Experimental Skills in JEE Main?
Experimental Skills (Physics) has been asked 47 times in the 111 JEE (Main) shift papers from 2020–2025: about 0.4 questions a paper, 2% of all Physics questions. It is the 20th most-asked of 20 Physics chapters. The 2025 shifts had 4 from it in all.
Which topics of Experimental Skills are asked most in JEE Main?
Vernier calipers and screw gauge (36), Electricity experiments (3), Optics experiments (3), Properties of matter experiments (2), counted over the papers from 2020–2025.
Is Experimental Skills important for JEE Main 2027?
It is in the syllabus in force, so it can be asked. By past papers it ranks 20 of 20 in Physics; use that to decide how much time it gets, not whether to study it.
Where can I solve Experimental Skills JEE Main previous year questions?
On Nikaalle, free: sign up and practise every past JEE Main question from Experimental Skills 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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