(a) A person listens to a source of sound of frequency `350 Hz` standing at a distance of `500 m`. What is the time interval between successive rarefactions from the source ?
(b) What is meant by the term lithotripsy ?

Explanation

(a) Time interval between two successive rarefactions `= T = (1)/(v) = (1)/(350) s`.
The distance of `500 m` has no significance.
(b) Lithotripsy is the technique of breaking gallstones or kidney stones using ultrasounds. (In greek, lithotripsy means stone breaking).