Question

Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?

a.) They have a wavelength of two cycles per second.
b.) They have a frequency of 2 hertz.
c.) They have a frequency of 4 hertz.
d.) We can calculate the wavelength of the ripples from their frequency.

Answer 1

Answer:

b.) They have a frequency of 2 hertz.

Explanation:

The frequency of a wave is the number of complete oscillations (cycles) made by the wave in one second.

Instead, the wavelength is the distance between two consecutive crests (highest position) or 2 troughs (lowest position) of the wave.

In this problem, we are told that the leaf does two full up and down bobs: this means that it completes 2 full cycles in one second. Therefore, its frequency is

$f =2 s^{-1}$

where $s^{-1}$ is called Hertz (Hz). So, the correct answer is

b.) They have a frequency of 2 hertz.