Concepts Of Physics MCQ Edition [Volume 1]PhysicsSound Waves
In a Kundt's tube apparatus, a steel rod of length 1.0 m is clamped at its centre. It is set into vibration in its fundamental mode with a frequency of 2600 Hz . The lycopodium powder dispersed inside the tube gathers into heaps that are separated by 6.5 cm . Determine the speed of sound in steel and in air, respectively.
Options
- A2600 m/s and 338 m/s
- B5200 m/s and 338 m/s
- C5200 m/s and 169 m/s
- D2600 m/s and 169 m/s
Correct answer
B. 5200 m/s and 338 m/s
Step-by-step solution
For the steel rod clamped at the centre and vibrating in its fundamental mode, the centre is a node and the ends are antinodes. Length of the rod, L = _ steel 2 _ steel = 2L = 2 1.0 = 2.0 m Speed of sound in steel, v_ steel = f _ steel = 2600 2.0 = 5200 m/s In the Kundt's tube, the distance between consecutive heaps of lycopodium powder represents the distance between consecutive nodes of the standing wave in air. _ air 2 = 6.5 cm = 0.065 m _ air = 2 0.065 = 0.13 m Speed of sound in air, v_ air = f _ air = 2600 0.1