Question

A body sends waves \(150\) mm long through medium P and \(0.30\) m long in medium Q. If the velocity of wave in medium P is \(80\) cm/s, the velocity of wave in medium Q in m/s is

• A. \(1.6\)
• B. \(2.0\)
• C. \(3.2\)
• D. \(3.8\)

Hint:

The frequency of the source stays the same when the wave enters another medium.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
The frequency is fixed by the source, so \(\dfrac{v}{\lambda}\) is the same in both media.

Step 2: Convert
\(\lambda_{P}=150\) mm \(=0.15\) m and \(\lambda_{Q}=0.30\) m. \(v_{P}=80\) cm/s \(=0.8\) m/s.

Step 3: Calculation
\(v_{Q}=v_{P}\times\dfrac{\lambda_{Q}}{\lambda_{P}}=0.8\times2=1.6\) m/s.

Final Answer:
The wave speed in medium Q is 1.6 m/s. \[ \boxed{\text{(A) }1.6} \]