Page 137 - Physics - XI

Result

Velocity of sound in air at room temperature (t =______ °C) using a resonance tube by two resonance
position method is ______ ms .
–1
Precautions
1. The resonance tube apparatus should be kept vertical.

2. The tuning fork should be struck gently against a soft rubber pad.
3. The vibrating tuning fork should be held horizontally over the open end of the tube.
4. The prongs of the vibrating tuning fork should not touch the tube.
5. There should be no leakage of water from the apparatus.

6. Reading of resonance positions should be taken from water level rising as well as falling in the tube.
7. Reading of the lower meniscus of water level should be taken with the help of a set-square.

Sources of Error
1. The resonance tube may not be vertical.

2. Pitch cock may be loose.
3. The presence of moisture in the tube will increase the velocity sound.

VIVA VOCE

Q1. Can you specify the position of nodes and anti-nodes in the air column?
Ans. The node lies at the surface of the water level while the anti-node lies at the open end of the metallic
tube.
Q2. State the principle of working of a resonance tube.
Ans. It works on the principle of the resonance of air column.

Q3. What is resonance?
Ans. The phenomenon of setting one body into vibrations with its natural frequency with the help of
another body vibrating with the same frequency is called resonance.
Q4. Is the velocity of sound temperature dependent? If yes, write the relation. (NCERT)
Ans. Yes, the velocity of sound is temperature dependent. The velocity of sound depends on temperature

t
as vv 1 , v is the velocity of sound at 0°C and v is the velocity of sound at t °C.
0 0
273
Q5. Name the phenomenon responsible for resonance in this experiment. (NCERT)
Ans. In this experiment, for resonance to occur, a node must be formed at the closed end and an anti-node
must be formed at the open end of a tube. So, due to this reason, the frequency of the air column
becomes equal to the natural frequency of the tuning fork.

Q6. Write two other examples of resonance of sound from day to day life. (NCERT)
Ans. If we consider musical instruments, then there can be the example like strings of violin, length of the
tube in a fl ute. While in the case of mechanical resonance, example like breaking of the wine glass
with sound at precise resonant frequency of the glass.

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