Doppler Effect and Relative Velocity – Rankers Physics

Sound Wave and its Characteristics: Practice Problem & Solution

Assertion (A): When there is no relative velocity between source and observer then observed frequency is same as emitted. Reason (R): Velocity of sound is zero when there is no relative velocity between source and observer.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Sound Wave and its Characteristics. Understanding the underlying formula is key to arriving at the correct answer below:

According to the Doppler effect, the observed frequency matches the emitted frequency only when there is no relative motion between the source and observer. So, Assertion (A) is true. The velocity of sound is a property of the medium and is non-zero in an ideal medium, irrespective of relative motion between source and observer. So, Reason (R) is false. Thus, (A) is true but (R) is false.

Leave a Reply

Your email address will not be published. Required fields are marked *

Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Assertion (A): A vibrating tuning fork sounds louder, when its stem is pressed against a desk top. Reason (R): When a sound wave is incident on the surface of a desk, it is totally reflected.  
2. A stretched string resonates with tuning fork frequency $512 \text{ Hz}$ when length of the string is $0.5 \text{ m}$. The length of the string required to vibrate resonantly with a tuning fork of frequency $256 \text{ Hz}$ would be: (1993)
3. The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is $20 \text{ cm}$, the length of the open organ pipe is: (2018)
4. Assertion (A): An acoustic guitar depends for its sound on the acoustic resonance produced in the hollow body of the instrument by the oscillations of the strings. Reason (R): Electric guitar is a solid instrument that based upon resonance. (In electric guitar the oscillations of the metal strings are sensed by electric "pickups" that send it to an amplifier).  
5. Assertion (A): Sound is produced due to vibratory motion, but a vibrating pendulum does not produce audible sound. Reason (R): A vibrating source always produce audible sound.