Rewrite the following sentences according
to the instructions given after each. Make
other changes that may be necessary but
do not change the meaning of each
sentence.[8]
2 The teacher scolded him for coming late.
(Begin :He…….)
Answers
Answer:
CHARACTERISTICS OF SOUND:
Loudness: The degree of the sensation produced on the ear is known as LOUDNESS of
sound. It is expressed in decibels (dB).
Example: Sound produced from drums in the school assembly.
Feebleness: The lack of volume or loudness is known as FEEBLENESS of sound.
Example: Sound produced while taking pledge in the school assembly.
Loudness and feebleness of a sound are measured in decibels(dB)
Amplitude: The maximum displacement of a vibrating body from its mean position is
known as AMPLITUDE.
Loudness and feebleness of a sound depend on AMPLITUDE of vibration.
Pitch: The Shrillness of a sound is known as PITCH.Activity: To identify pitch of a sound
1. Take two hack-saw blades or metal
scales of 30 cm length and a brick.
2. Place the first blade/scale on the
table such that 10 cm portion is on
the table and 20 cm portion is in air.
3. Place the second blade/scale on the
table with 25 cm portion on the
table and 5 cm portion in air.
4. See that the gap between two
blades is 10 cm and place the brick
(as weight) on the scales.
5. Vibrate both blades with same
force. Observe the vibrations and hear the sounds produced.
6. We observe that the number of vibrations produced is less in first blade/scale when
compared to the second blade/scale.
7. The sound produced by the second blade/scale is shriller when compared to the sound
produced by the first blade/scale.
MUSIC AND NOISE:
Music: The sound which is pleasant to hear is called MUSIC.
Example: Sounds produced by musical instruments.
Noise: The sound which is unpleasant to hear is called NOISE.
Example: Irregular sounds produced in a class-room by the students.
AUDIBLE RANGE OF HUMAN BEINGS:
Note: The number of vibrations per second is called FREQUENCY.
1. The sounds that a normal human being can hear are called AUDIBLE SOUNDS.
2. The frequency of the audible sound ranges from 20 vibrations/second to 20000
vibrations/second.
3. The frequency of inaudible sounds is less than 20 vibrations/second or more than
20000 vibrations/secon
Explanation:
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Answer:
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