Physics · chapter PYQs

Waves, on the exam screen.

3 questions from NEET 2026, Re-NEET 2026, NEET 2020, 3 minutes, marked +4 / −1. See them with solutions.

Waves · PYQs

Candidate: You

Time Left

Q1/3

Question 1 · NEET 2026 · Q21 · +4 / −1
For a travelling harmonic wave $y(x, t) = 2.0\cos 2\pi(10t - 0.0080x + 0.35)$ , where $x$ and $y$ are in cm and $t$ in s, the phase difference between oscillatory motion of two points separated by a distance of 0.5 m is:
Answer and explanation
Answer: (2)
The spatial part of the phase is $2\pi(0.0080)x$ with x in cm, so the wave number term gives phase difference $\Delta\phi = 2\pi(0.0080)\,\Delta x$ . Converting the separation to centimetres, $\Delta x = 0.5\ \text{m} = 50\ \text{cm}$ , so $\Delta\phi = 2\pi \times 0.0080 \times 50 = 0.8\pi$ rad (option (2)). The wrong answers arise from failing to convert 0.5 m into 50 cm.
Question 2 · Re-NEET 2026 · Q4 · +4 / −1
For sound waves, if the number of nodes for the 5th harmonic of an open-ended pipe is $n$ and that for the 9th harmonic of the same pipe with one of its ends closed is $m$ , the ratio $\frac{n}{m}$ is
Answer and explanation
Answer: (3)
An open-open pipe has antinodes at both ends, and its $p$ -th harmonic contains exactly $p$ nodes, so the 5th harmonic gives $n = 5$ . A closed pipe supports only odd harmonics, with a node at the closed end and an antinode at the open end; its $q$ -th harmonic ( $q$ odd) contains $\frac{q+1}{2}$ nodes, so the 9th harmonic gives $m = \frac{10}{2} = 5$ . The ratio is therefore 1. NCERT Class 11, Waves (standing waves in air columns).
Question 3 · NEET 2020 · Q161 · +4 / −1
In a guitar, two strings A and B made of the same material are slightly out of tune and produce beats of frequency 6 Hz. When tension in B is slightly decreased, the beat frequency increases to 7 Hz. If the frequency of A is 530 Hz, the original frequency of B will be
Answer and explanation
Answer: (1)
Initially |fB - 530| = 6. Decreasing B's tension lowers fB; because the beat frequency then increases, B was already below 530 Hz. Thus fB = 530 - 6 = 524 Hz. Chapter: Waves.