S1 & S2 are sources of the sound of frequency 656 Hz. S1 is moving along OP and S2 is moving on the circle in an anticlockwise direction with a constant speed of 4√2 m\s. P is a detector that is fixed. Select the correct options (Vsound=300m\s)
- When S2 is at Q, Then frequency it detected by the detector is approximately 647 Hz.
- When S2 is at Q, Then frequency it detected by the detector is 327 Hz.
- When S2 is at R and S1 is coming toward P with a velocity of 4m/s, Then the beat frequency it detected by the detector is 8.86 Hz.
- When S2 is at R and S1 is coming toward P with a velocity of 4m/s, Then the beat frequency it detected by the detector is 2.56 Hz.
The Correct Option is A, C
Solution and Explanation
\(f'=\frac{656\times300}{304}\)
\(f'=647.36\,Hz\)
Hence, Option (A) is correct.
From S2 , \(f'=656\,[\frac{300}{300+4\sqrt2\,cos\,90}]\)
\(f'=656\)
From S1, \(f''=656\,[\frac{300}{300-4}]\)
\(f''=664.86\)
Beat frequency = \(f''-f'\) = \(664.86-656\) = 8.86 Hz
br>Hence, Option (C) is also correct.
Top Questions on doppler effect
- A passenger is sitting in a fast moving train. The engine of the train blows a whistle of frequency N. If the apparent frequency of sound heard by the passengers is \( N' \), then:
- MHT CET - 2025
- Physics
- doppler effect
- A source (S) of sound has frequency\( 240 Hz\). When the observer (O) and the source move towards each other at a speed \(v\) with respect to the ground (as shown in Case 1 in the figure), the observer measures the frequency of the sound to be \(288 Hz\). However, when the observer and the source move away from each other at the same speed v with respect to the ground (as shown in Case 2 in the figure), the observer measures the frequency of sound to be \(n\) Hz. The value of \(n\) is _____.
- JEE Advanced - 2024
- Physics
- doppler effect
- A galaxy is moving away from the Earth so that a spectral line at 6000 Å is observed at 6300 Å. Then the speed of the galaxy with respect to the Earth is
- KCET - 2024
- Physics
- doppler effect
- A train is moving with a speed of \(10 m/s\) towards a platform and blows a horn with frequency \(400 Hz\). Find the frequency heard by a passenger standing on the platform. Take speed of sound = \(310 m/s\).
- JEE Main - 2023
- Physics
- doppler effect
- A car P travelling at 20 \(ms^{–1}\) sounds its horn at a frequency of 400 Hz. Another car Q is travelling being the first car in the same direction with a velocity 40 \(ms^{–1}\) . The frequency heard by the passenger of the car Q is approximately [Take, velocity of sound = 360 \(ms^{–1}\) ]
- JEE Main - 2023
- Physics
- doppler effect
Questions Asked in JEE Advanced exam
- Let $ x_0 $ be the real number such that $ e^{x_0} + x_0 = 0 $. For a given real number $ \alpha $, define $$ g(x) = \frac{3xe^x + 3x - \alpha e^x - \alpha x}{3(e^x + 1)} $$ for all real numbers $ x $. Then which one of the following statements is TRUE?
- JEE Advanced - 2025
- Fundamental Theorem of Calculus
Two identical concave mirrors each of focal length $ f $ are facing each other as shown. A glass slab of thickness $ t $ and refractive index $ n_0 $ is placed equidistant from both mirrors on the principal axis. A monochromatic point source $ S $ is placed at the center of the slab. For the image to be formed on $ S $ itself, which of the following distances between the two mirrors is/are correct:
- JEE Advanced - 2025
- Ray optics and optical instruments
- Let $$ \alpha = \frac{1}{\sin 60^\circ \sin 61^\circ} + \frac{1}{\sin 62^\circ \sin 63^\circ} + \cdots + \frac{1}{\sin 118^\circ \sin 119^\circ}. $$ Then the value of $$ \left( \frac{\csc 1^\circ}{\alpha} \right)^2 $$ is \rule{1cm}{0.15mm}.
- JEE Advanced - 2025
- Some Applications of Trigonometry
- A geostationary satellite above the equator is orbiting around the earth at a fixed distance $r_1$ from the center of the earth. A second satellite is orbiting in the equatorial plane in the opposite direction to the earth’s rotation, at a distance $r_2$ from the center of the earth, such that $r_1 = 1.21 \, r_2$. The time period of the second satellite as measured from the geostationary satellite is $\frac{24}{p}$ hours. The value of $p$ is ___
- JEE Advanced - 2025
- Orbital Mechanics
The major products obtained from the reactions in List-II are the reactants for the named reactions mentioned in List-I. Match each entry in List-I with the appropriate entry in List-II and choose the correct option.
- JEE Advanced - 2025
- Organic Chemistry - Some Basic Principles and Techniques
JEE Advanced Notification
Concepts Used:
Doppler Effect
The Doppler effect is a phenomenon caused by a moving wave source that causes an apparent upward shift in frequency for observers who are approaching the source and a visible downward change in frequency for observers who are retreating from the source. It's crucial to note that the impact isn't caused by a change in the source's frequency.
The Doppler effect may be seen in any wave type, including water waves, sound waves, and light waves. We are most familiar with the Doppler effect because of our encounters with sound waves