What do you mean by a vibratory motion?
The to and fro motion in which a body assumes a new shape during its motion, is called vibratory motion.
What is sound?
Sound is a form of energy that produces the sensation of hearing in our ears.
How is sound produced?
Sound is produced when a body vibrates. In other words, each source of sound is a vibrating body.
The bees do not have voice-boxes but they still make sound. How?
Bees do not have voice-boxes. They make sound by moving their wings up and down very fast.
Describe an experiment to show that sound can travel in water.
Fill a balloon with water. Hold it near your ear. Now keep a watch gently to the other side of the balloon. You will hear the ticking sound of the watch. This shows that sound travels in water.
Define the term Amplitude.
The maximum displacement of a wave on either side of its mean position is known as amplitude. It is measured in metre.
Define Time period.
The time taken by a wave to complete one vibration is known as its time period. It is always denoted by the letter T and is measured in second.
The number of vibrations produced by the source of sound wave in one second is known as its frequency. It is denoted by F or N. The unit of frequency is hertz which is denoted by the symbol Hz
What are ultrasonics? Can you hear the ultrasonic sound?
Sounds of frequency higher than 20,000 Hz are called ultrasonic sound. We annot hear ultrasonic sounds.
What are infrasonics? Can you hear them?
Sounds of frequency lower than 20 Hz are called infrasonic sounds. We cannot hear the infrasonic sounds.
Name the two characteristics of sound which differ any two sounds from each other.
Two characteristics of sound:
On what factor does the loudness of a sound depend?
The loudness of a sound depends on the amplitude of vibrations of the vibrating body producing the sound. Greater the amplitude of Vibrations, louder is the sound produced.
How does the loudness of sound produced depend on the vibrating area of the body?
The loudness of sound also depends on the area of the vibrating body. Greater the area of the vibrating body, louder is the sound produced.
The outer case of the bell in a temple is made big. Give a reason.
In temples, you must have noticed that a bell with a bid case produces a louder sound than that with a small case. Dependence of loudness on amplitude of vibration.
State the factors on which the pitch of a sound depends.
Pitch is the high or low frequency of a sound. The pitch of a sound depends on its frequency.
Differ b/w a high pitch sound & low pitch sound.
A sound of high frequency is said to have a higher pitch while a sound of low frequency is said to have a low pitch.
how does a man's voice differ from a woman's voice?
The voice of a girl is shriller than that of a boy because the voice of the girl is of a higher pitch. The voice of a child is shriller than that of an adult.
Name the characteristics which differentiates two sounds of the same pitch and same loudness.
Quality is the characteristics which distinguishes two sounds of same pitch and same loudness.
You recognize your friend by hearing her voice on a telephone. Explain.
We recognize the voice of a person without seeing them, due their quality.