Wave Motion 3 Question 4
4. A source of sound of frequency $600 Hz$ is placed inside water. The speed of sound in water is $1500 m / s$ and in air it is $300 m / s$. The frequency of sound recorded by an observer who is standing in air is
(a) $200 Hz$
(b) $3000 Hz$
(c) $120 Hz$
(d) $600 Hz$
(2004, 2M)
$$ y=4 \sin \left(\frac{\pi x}{15}\right) \cos (96 \pi t) $$
where, $x$ and $y$ are in $cm$ and $t$ is in second.
$(1985,6$ M)
(a) What is the maximum displacement of a point at $x=5 cm$ ?
(b) Where are the nodes located along the string?
(c) What is the velocity of the particle at $x=7.5 cm$ at $t=0.25 s$ ?
(d) Write down the equations of the component waves whose superposition gives the above wave.
Show Answer
Answer:
Correct Answer: 4. (d)
Solution:
- The frequency is a characteristic of source. It is independent of the medium. Hence, the correct option is (d).
