Question

wave covers 30cm in 5s, if the distance between a crest and its neighbouring trough is 1.5cm, (a) What is the wavelength? (b) How many circles can be formed in 15s?

Answer 1

$(a)\ \ \lambda=2\cdot1.5=3\ (cm)$

$(b)\ \ l=(30/5)\cdot15=90\ (cm)$

$n=90/3=30.$