Answer:
Solution given:
No of waves[N] =20crests & 20 troughs
=20waves
Time[T]=4seconds
distance[d]=3cm=0.03m
Now
Wave length=3cm=3 × [tex] {10}^{ - 2}m [/tex]
Frequency=[tex] \frac{No of waves}{time}[/tex]
=[tex] \frac{20}{4} [/tex]=5Hertz
and
Wave speed:wave length×frequency=3 × [tex] {10}^{ - 2}m [/tex]×5=1.5 × [tex] {10}^{ - 1} \tt{ {ms}^{ - 1}} [/tex].
