JEE PYQ: Waves And Sound Question 28
Question 28 - 2019 (09 Apr Shift 2)
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:
(1) 180 m/s, 80 Hz
(2) 320 m/s, 80 Hz
(3) 320 m/s, 120 Hz
(4) 180 m/s, 120 Hz
Show Answer
Answer: (2)
Solution
$\frac{3\lambda}{2} = 2$ or $\lambda = \frac{4}{3}$ m
Velocity, $v = f\lambda = 240 \times \frac{4}{3} = 320$ m/sec
Also $f_1 = \frac{240}{3} = 80$ Hz
BETA
