A device called oscillator is used to send waves along a stretched string. The string is 20 cm long, and four complete waves fit along its length when the oscillator vibrates 30 times per second. For the waves on the string:
(a) what is their wavelength?
(b) what is their frequency?
(c) what is their speed?

As given total length of the string $=20\ cm$

And it is also given that four complete waves fit along total strings length.

Number of vibration per second $=30$

So,

(a). Wavelength $=$ length of string that fits a complete wave

$=\frac{total\ length\ of string}{4}$  [four complete waves fit along total strings length.]

$=\frac{20\ cm}{4}$

$=5\ cm$

$=0.05\ m$

So, the wavelength is $0.05\ m$.

(b). Frequency$=$vibrations per second$\times$number of total waves

$=30\ s\times4$

$=120\ Hz$

(c). Speed $=$wavelength(\lamda)\times frequency(f)$

$=0.05\times120\ Hz$

$=6\ m/s$

Therefore, speed of the wave is $6\ m/s$.

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Updated on: 10-Oct-2022

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