Question

Explain identification of pitch or shrillness of sound with the help of an activity. 

(OR) 

What are the characteristics of sound? Explain the procedure to identity the pitch of sound.

a) What difference do you notice in number of vibrations of two blades?

b) What difference do you notice in the quality of sound produced by them?

Answer 1

Chardcteristics sound are 1) Loudness 2) Pitch 3) Quality.

Aim: Identifying pitch or shrillness of a sound.

Materials required: A wooden table, two hack-saw blades or metal scales of 30cm length and a brick. 

Procedure:

Place the first blade/scale on the table, with 10cm portion of the blade on the table and rest of it in air. Keep a brick as weight on the 10 cm portion of the blade/scale kept on the table. Vibrations of hack-saw blades Place the second blade/scale on the table (see that the gap between these two blades is 10cm), with 25cm on the table and 5cm in air. Keep a brick as weight on the scale/blade.

Vibrations of hack saw blades

Vibrate both blades with same force. Observe the vibrations and listen to the sounds produced.

Repeat the same 2-3 times and record observations in the table showed below

Blade length in air	Vibrations	Sound
Blade 1 : 20cm	50	Less shrillness
Blade 2 : 5cm	90	More shrillness

a) The number of vibrations in 5 cm blade is more.

b) The sound produced by 5 cm blade is more shrill when compared to that of 20 cm blade.