Question

Write about "e c h o "......!

Answer 1

ECHO

the the sound wave bounce back or reflect back after striking to a hard surface is called echo .

in ECHO we heard repetition of sound.

• for echo there must be a sufficient gap between body and the hard surface as well as sufficient time gap too required.

Answer 2

Answer:

Echo:- Repeation of a sound for many times due to reflection is known as an echo.

Explanation:

If d is the distance between the source and the reflector then equation will be as

2d = vt

or

d = vt/2

where;

v = speed of the sound

t = time taken of the echo

Explaination:-

Minimum Distance required for echo:-

As generally effect of any sound exist for 1/10 second in our ears so if the sound comes back before 1/10 second then there will be not be any prominent or distinguished original sound which means echo is not formed.

Therefore we can find the minimum distance as

$\begin{lgathered}\sf{d_{minimum} = \frac{v \times t}{2} } \\ \\ \sf{d_{minimum} = \frac{330}{2}x \frac{1}{10} } \\ \\ \sf{d_{minimum} = \frac{330}{20} } \\ \\ \sf{d_{minimum} = \frac{ \cancel33}{ \cancel2} } \\ \\ \boxed{\sf{d_{minimum} = 16.5m}}\end{lgathered}$