Question

A longitudinal wave is produced on a slinky toy. The wave travels at a speed of $30\text{cm/s}$ and the frequency of the wave is $20\text{Hz}$. What is the minimum separation between two consecutive compressions of the slinky toy ?

• A. $2.5\text{cm}$
• B. $0.5\text{cm}$
• C. $1.5\text{cm}$
• D. $1.8\text{cm}$

Answer 1

The correct option is C $1.5\text{cm}$

Given,
Speed of wave, $v=30\text{cm/s}$
Frequency of the wave, $f=20\text{Hz}$
We know that, minimum separation between two consecutive compressions or rarefactions of the slinky will be equal to wavelength of the longitudinal wave.
So, from the formula for speed of a wave $v=\lambda f$
we get, $\lambda =\frac{v}{f}$
From the data given in the question ,
$\lambda =\frac{30}{20}=1.5\text{cm}$
Thus, option (c) is the correct answer.