Match the pairs. Group 'A' Group 'B' (a) Flute (1) Frequency less than 20 Hz (b) Frequency (2) Frequency more than 2000 Hz (c) Sound level (3) Vibrations in the air (d) Ultrasonic Sound (4) Measured in Hz (e) Infrasonic Sound (5) Decibel

Flute Vibrations in the air The flute is a wind instrument and the sound is produced by the vibration of the air column. The air particles are made to vibrate by blowing across a blow hole. The pitch of a wind instrument can be changed by altering the length of the air column. Frequency Measured in Hz Frequency is defined as the number of vibrations produced by a vibrating object in 1 s . Frequency can also be defined as the number of waves passing through a point in one second and its SI unit is hertz ( Hz ). Sound level Decibel The loudness of sound is measured in decibels (dB). It signifies the sound pressure level. Human ears can pick up sound from 10 dB to 180 dB . A loudness of sound is considered normal if it is between 50 dB to 60 dB . A normal human being can tolerate loudness of 80 dB . Ultrasonic sound Frequency more than 20000 Hz Ultrasonic sound refers to the sound whose frequency is above than audible sound. and normally includes anything over 20000 Hz . Infra sound Frequency less than 20 Hz If the frequency of the vibrations is less than 20 Hz, then the human ear cannot perceive them. Such vibrations are called infrasonic vibrations. Group A Group B a. Flute 3. Vibration in the air b. Frequency 4. Measured in Hz c. Sound level 5. Decibel d. Ultrasonic sound 2. Frequency more than 20000 Hz e. Infrasonic sound 1. Frequency less than 20 Hz

E M B I B E

General Science Standard Seven>Chapter 18 - Sounds : Production of Sound>Exercise>Q 1

EASY

7th Maharashtra Board

IMPORTANT

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The frequency of sound is measured in .

(Choose from the following: decibel/ hertz)

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Important Questions on Sounds : Production of Sound

EASY

7th Maharashtra Board

IMPORTANT

General Science Standard Seven>Chapter 18 - Sounds : Production of Sound>Exercise>Q 1

If _____ of sound is decreased its loudness also decreases.

EASY

7th Maharashtra Board

IMPORTANT

General Science Standard Seven>Chapter 18 - Sounds : Production of Sound>Exercise>Q 1

A medium is necessary for _____ of sound.

MEDIUM

7th Maharashtra Board

IMPORTANT

General Science Standard Seven>Chapter 18 - Sounds : Production of Sound>Exercise>Q 2

Match the pairs.

Group 'A'	Group 'B'
(a) Flute	(1) Frequency less than $20 Hz$
(b) Frequency	(2) Frequency more than $2000 Hz$
(c) Sound level	(3) Vibrations in the air
(d) Ultrasonic Sound	(4) Measured in $Hz$
(e) Infrasonic Sound	(5) Decibel