Question

When source of sound and observer both are moving towards each other, the observer will hear}

• A. low frequency, low wavelength.
• B. low frequency, high wavelength.
• C. high frequency, low wavelength.
• D. high frequency, high wavelength.

Hint:

Towards $\to$ Frequency $\uparrow$, Wavelength $\downarrow$. Away $\to$ Frequency $\downarrow$, Wavelength $\uparrow$.

Answer 1

The Correct Option is C

Step 1: Doppler Effect Concept
When the source and observer move towards each other, the relative speed of sound increases for the observer, leading to a higher apparent frequency ($n'>n$).
Step 2: Wavelength Analysis
When the source moves towards the observer, the waves are "bunched up" in front of the source, leading to a decrease in the observed wavelength ($\lambda'<\lambda$).
Step 3: Conclusion
Apparent frequency increases and apparent wavelength decreases.
Final Answer: (C)