Experiment 08 · Setup Diagram

Kundt's Tube

The generator sets the frequency, the amplifier gives it enough power to drive the air, and the reflector at the far end sends the sound back on itself. Only the spacing of the dust heaps has to be measured.

Procedure

1. 1.

   Spread the saw dust particles uniformly along the length of Kundt's tube.

2. 2.

   Connect the A.F.G. with the amplifier, and the amplifier to the speaker.

3. 3.

   Place the speaker at one end of the Kundt's tube and the reflector at the other end.

4. 4.

   Set the A.F.G. at 1 kHz and adjust the length of the vibrating air column by moving the reflector until well defined loops are obtained.

5. 5.

   Measure the distance between a specific number of loops, and from it find the length of one loop and hence the wavelength.

   l = L/N, λ = 2l

6. 6.

   Calculate the velocity of sound in air using the formula.

7. 7.

   Repeat the same procedure for 1.5 kHz, 2 kHz and 2.5 kHz.

8. 8.

   Find the mean velocity. This is the velocity of sound in air at room temperature. Using the formula, find the velocity of sound at 0 °C.

Formula

v_t = nλ

v_t = v₀(1 + αt/2)