Question

State three condition necessary forhearing sound

Answer 1

Answer:

${\boxed{\boxed{\blue{Conditions\:necessary\:for\:hearing\:sound:}}}}$

• The reflector (screen) must have the size greater than the wavelength and amplitude of the sound wave(s).

• The sound wave should be of sufficient intensity.

• The distance between the reflector and the person should be more than 17m.***

*** Derivation:

Experimentally it has been proved that the sensation of sound in our ears persists for 0.1s.

Hence the reflected sound wave should reach the ears after 0.1s else it will overlap with the original one and no distinct echo will be heard.

Taking time(t) = 0.1s and speed of sound(v) as 340 m/s

Let distance between the reflector and person be "s"

Thus distance travelled by sound is 2s.

Speed = distance(2s) / time

Therefore,

v = 2s/t

340 = 2s / 0.1

s = 34/2

s = 17m

Therefore the minimum distance between the reflector and the person must be ${\huge{\boxed{\green{17m}}}}$.

Hope this helps you.