1. Choose the correct answer.
1. Which of the following vibrates when a musical note is produced by the cymbals in a orchestra?
(a) stretched strings
(b) stretched membranes
(c) air columns
(d) metal plates
[Answer: (d) metal plates]
2. Sound travels in air:
(a) if there is no moisture in the atmosphere.
(b) if particles of medium travel from one place to another.
(c) if both particles as well as disturbance move from one place to another.
(d) if disturbance moves.
[Answer: (d) if disturbance moves]
3. A musical instrument is producing continuous note. This note cannot be heard by a person having a normal hearing range. This note must then be passing through
(d) empty vessel
[Answer: (b) vacuum]
4. The maximum speed of vibrations which produces audible sound will be in
(a) sea water
(b) ground glass
(c) dry air
(d) human blood
[Answer: (b) ground glass]
5. The sound waves travel faster
(a) in liquids
(b) in gases
(c) in solids
(d) in vacuum
[Answer: (c) in solids]
II. Fill in the blanks.
1. Sound is a longitudinal mechanical wave and needs a material medium to travel.
2. Number of vibrations produced in one second is Frequency.
3. The velocity of sound in solid is greater than the velocity of sound in air.
4. Vibration, of object produces Sound.
5. Loudness is proportional to the square of the Amplitude of vibraion of sound.
6. Stethoscope is a medical instrument used for listening to sounds produced in the body.
7. The repeated reflection that results in persistence of sound is called Reverberation.
III. Match the following :
Tuning fork - The point where density of air is maximum.
Sound - Maximum displacement from the equilibrium position.
Compressions - The sound whose frequency is greater than 20,000 Hz
Amplitude - Longitudinal wave
Ultrasonics - Production of sound
Answer: 1-e, 2-d, 3-a, 4-b, 5-c
Tuning fork - Production of sound
Sound - Longitudinal wave
Compressions - The point where density of air is maximum.
Amplitude - Maximum displacement from the equilibrium position.
Ultrasonics - The sound whose frequency is greater than 20,000 Hz