### Waves - Result Question 60

#### 62. Two vibrating tuning forks produce progressive waves given by $y_1=4 \sin 500 \pi t$ and $y_2=2 \sin 506 \pi t$. Number of beats produced per minute is

(a) 360

(b) 180

(c) 60

(d) 3

[2005]

## Show Answer

#### Answer:

Correct Answer: 62. (b)

Solution:

- (b) Equation of progressive wave is given by

$ y=A \sin 2 \pi f t $

Given $y_1=4 \sin 500 \pi t$ and $y_2=2 \sin 506 \pi t$.

Comparing the given equations with equation of progressive wave, we get

$2 f_1=500 \Rightarrow f_1=250$

$2 f_2=506 \Rightarrow f_2=253$

Beats $=f_2-f_1=253-250=3$ beats $/ sec$

$=3 \times 60=180$ beats $/$ minute.