Waves
2 solved JEE Physics previous year questions on Waves, each with the correct answer and a full explanation.
Q1
A closed organ pipe (closed at one end) is excited to support the third overtone. It is found that air in the pipe has
✓ Correct answer: d) four nodes and four antinodes
ExplanationA closed organ pipe has a node at the closed end and an antinode at the open end.The harmonics that can be excited are odd multiples of the fundamental frequency, corresponding to specific standing wave patterns.The fundamental frequency (first harmonic) has 1 node and 1 antinode.The first overtone (third harmonic) has 2 nodes and 2 antinodes.The second overtone (fifth harmonic) has 3 nodes and 3 antinodes.The third overtone (seventh harmonic) has 4 nodes and 4 antinodes.Therefore, when a closed organ pipe is excited to support the third overtone, the air in the pipe has four nodes and four antinodes.
Q2
A standing wave having 3 nodes and 2 antinodes is formed between two atoms having a distance between them. The wavelength of the standing wave is
✓ Correct answer: c) 1.21 Å
ExplanationIdea (NCERT): For standing waves with nodes at both ends, and the number of antinodes Here: 3 nodes & 2 antinodes
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