A pebble is dropped in a lake;and it produces ripples with a frequency of 0.50 Hz.When should a second pebble be dropped at the same place to produce destructive interference?
A)0.50 s after the first
B)0.75 s after the first
C)1.0 s after the first
D)1.5 s after the first
E)2.0 s after the first

Question

Quizplus · Accepted Answer

Destructive interference occurs when two waves are out of phase by 180 degrees, which corresponds to half a wavelength or half a period in time. Given the frequency of 0.50 Hz, the period (T) is the reciprocal of the frequency, T = 1/f = 1/0.50 Hz = 2.0 s. Half of this period is 1.0 s, so dropping the second pebble 1.0 s after the first will result in destructive interference.

A Pebble Is Dropped in a Lake;and It Produces Ripples