English Medium Class 9 - CBSE Question Bank Solutions for Science

What conclusion can be obtained from the observation that when the prongs of a sound making tuning fork touch the surface of water in a beaker, the water gets splashed?

State whether the following statement is true or false :
Sound produced by a vibrating body travels to our ears by the actual movement of air.

What will be the change in the wavelength of a sound wave in air if its frequency is doubled?

Name four ways in which sound can be produced.

Which object is vibrating when the following sounds are produced?

(i) The sound of a sitar
(ii) The sound of a tabla
(iii) The sound of a tuning fork
(iv) The buzzing of a bee or mosquito
(v) The sound of a flute

Give reason for the following :
In most of the cases, we cannot see the vibrations of a sound producing object with our eyes.

Describe a simple experiment to show that the prongs of a sound producing tuning fork are vibrating.

How is sound produced? Explain with the help of an example.

How does sound from a sound producing body travel through air to reach our ears? Illustrate your answer with the help of a labelled diagram.

Fill in the blank with suitable word.
When the frequency of the sound is increased, the wavelength ____________.

Draw the sketches of two waves A and B such that wave A has twice the wavelength and half the amplitude of wave B.

A device called oscillator is used to send waves along a stretched string. The string is 20 cm long, and four complete waves fit along its length when the oscillator vibrates 30 times per second. For the waves on the strings.

(a) what is their wavelength?
(b) what is their frequency
(c) what is their speed?

A sound producing body is at considerable distance from a man. There can be four different media W, X, Y and Z between the sound producing body and the man. The medium X brings the sound to man most quickly whereas medium Z takes the maximum time. The time taken by medium W in bringing sound to man is less than that of X but more than that of Z. The medium Y, however, fails to bring the sound from the sound producing body to the man. Which medium could be the one :
(a) having on fixed shape and no fixed volume?
(b) having a fixed volume but no fixed shape?
(c) having the same composition as that on the moon?
(d) having a fixed shape and a fixed volume?

Which of the following vibrates when a musical note is produced by the cymbals in an orchestra?

A musical instrument is producing a continuous note. This note cannot be heard by a person having a normal hearing rang. This note must then be passing through.