Question 179: Waves

Question

A string 2.0 m long and fixed at its ends is
driven by a 240 Hz vibrator. The string vibrates
in its third harmonic mode. The speed of the
wave and its fundamental frequency is :-

Accepted Answer

We have:
$$f = {{nv} \over {2l}}$$
$$240 = {{3 	imes v} \over {2 	imes 2}}$$
$$ \Rightarrow $$ v = 320 m/s
Fundamental frequency = $${v \over {2l}}$$ = 80 Hz.

Answer

180m/s, 80 Hz

Answer

180m/s, 120 Hz

Answer

320m/s, 120 Hz

Answer

320m/s, 80 Hz

Waves

A string 2.0 m long and fixed at its ends is driven by a 240 Hz vibrator. The string vibrates in its third harmonic mode. The speed of the wave and its fundamental frequency is :-

Choose the correct answer: