Apparatus:
Resonance tube apparatus, two tuning forks of known frequency, plumb line, vernier callipers. Rubber pad, thermometer, set squares, pinch cork and a beaker.
Observations:
Vernier Constant of vernier calliper = 0.01cm
Zero correction of vernier caliper =………………cm
Internal diameter of the resonance tube = (i) …cm (ii) …cm (iii) …cm
Mean corrected internal diameter of resonance tube (D) =……….cm
End correction = 0.3D =……….cm
Room temperature at the beginning =t1 0C
Room temperature at the beginning = t2 0C
Mean room temperature t = (t1 + t2) / 2 =………0C
Position of open end of the tube against the (X) = …………..cm
Calculation:
Velocity of sound in air at 00C =V0 =V1 -6It =……………..cm/sec.
Actual value of velocity of sound at 00C =………cm / sec.
Difference =………..cm /sec.
=………………%
Procedure:
Place the apparatus on a smooth horizontal surface and check the level of apparatus with a plumb line. If the apparatus is not horizontal then adjust it with foot screws. Find the vernier constant of a vernier callipers and check its zero error if any. Determine the internal diameter of the resonance tube at different places. Take its mean value and then the radius of the tube, also apply zero correction. Note the temperature of water at the start of the experiment as t; °C with a thermometer. Note the position of upper end of the resonance tube against the scale and assign it as ‘X’. Bring the water reservoir to its highest and then open the pinch-cock. Strike the tuning fork of known frequency say 512 Hz on rubber pad gently and held horizontally over the upper end of the tube. Lower the water level by opening the pinch cock gradually till the tube resounds with a loud note. Select the position on a resonance tube where the tube resounds maximum. Note this position with the help of set squares for the level falling. Similarly find the position when water level is rising. Take its mean value as “Y”. Subtract ‘X’from Y and find the value of t. Also note the temperature at the end of experiment as t₂ °C. Repeat this experiment with the second tuning fork and find the value of-for it. Now calculate the velocity of sound at 0°C as given above in the calculations.
Precautions:
1. The tuning fork should be struck gently on a rubber pad.
2. The resonance tube apparatus should be kept vertical.
3. The prong of the vibrating tuning fork should not touch at the upper end of the glass tube.
4. The vibrating tuning fork should be held horizontally above the open end of the tube.
5. Low meniscus of water surface should be read with the help of two set squares.
VIVA-VOCE
Q.1. what is meant by resonance?
Ans. Whenever a small periodic force acts upon a body and the body has the same natural period as that of the force, the resonance is produced i.e., the body is thrown into its natural vibration with a large amplitude.
Q.2. what is end correction?
Ans: The position of an antinode does not exactly lie at the center of the open end but slightly above it. This shift in the position of an antinode is called end correction and is found to be equal to 0.3 D, where ‘D’ is the internal diameter of tube.
Q.3. what is the effect of temperature on the velocity of sound?
Ans: It increases by 61 cm/sec for 1°C rise of temperature approximately.
Q.4. Define node and antinode.
Ans: (i) Node: A point in a vibrating body where the strain is maximum and amplitude is zero. Called node point.
(ii) Antinode: A point where strain is minimum and amplitude is maximum is called antinode point.
