NCERT Class 11 Physics Solutions: Chapter 15 – Waves-Part 8 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Question 15.14:

A wire stretched between two rigid supports vibrates in its fundamental mode with a frequency of 45 Hz. The mass of the wire is and its linear mass density is what is

The speed of a transverse wave on the string, and the tension in the string?


Mass of the wire,

Linear mass density,

Frequency of vibration,

∴ Length of the wire,

The wavelength of the stationary wave is related to the length of the wire by the relation:

Where, Number of nodes in the wire.

For fundamental node,

The speed of the transverse wave in the string is given as:

The tension produced in the string is given by the relation:

Question 15.15:

A meter-long tube open at one end, with a movable piston at the other end, shows resonance with a fixed frequency source (a tuning fork of frequency ) when the tube length is . Estimate the speed of sound in air at the temperature of the experiment. The edge effects may be neglected.


Frequency of the turning for

Since the given pipe is attached with a piston at one end, it will behave as a pipe with one end closed and the other end open, as shown in the given figure:

The Given Pipe is Attached with a Piston at One End, It Wil …

Such a system produces odd harmonics. The fundamental note in a closed pipe is g by the relation:


Length of the pipe,

The speed of sound is given by the relation: