Question

The dipper in a ripple tank vibrates at a frequency of $4.0Hz$ and the resulting wave pattern is photographed. The distance between the two crests shown is $20cm$. What is the speed of the wave ?

• A. $4cm{s}^{-1}$
• B. $5cm{s}^{-1}$
• C. $16cm{s}^{-1}$
• D. $20cm{s}^{-1}$

Answer 1

The correct option is C $16cm{s}^{-1}$

Answer is C.

The relationship between the speed (v) of a wave and its wavelength ($\lambda$) and frequency (f) is given as follows.
The equation is speed = wavelength * frequency. That is, $v=\lambda \times f$
In this case, the frequency is 4 Hz and the wavelength is 20 cm/5 as the distance of 5 crests and 5 troughs are given as 20 cm.
Therefore, v = 4 * 4 = 16 cm/s.
Hence, the speed of the wave is 16 cm/s.