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An observer while going on scooter hears sound of two sirens of same frequencies from two opposite directions. If he travels along the direction of one of the siren, then he
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Listens beats
Correct option is 2. Listens beats
Let the two waves produced due to the two sirens have frequency and velocity as $\nu_1, v_1$ and $\nu_2, v_2$
Since, both are sound waves, we have $v_1=v_2=v$
For one wave the traveler is moving towards the source,
$\therefore \nu^{\prime}=\nu\left(\frac{v-v_o}{v}\right)$
For the other the traveler is moving away from the source
$\therefore \nu^{\prime}=\nu\left(\frac{v+v_o}{v}\right)$
Seeing this, we can conclude that the waves are in phase with each other and are fluctuating repeatedly.
Since, they are sound waves they are periodic in nature. Hence, we got two waves that are periodic and are repeatedly fluctuating. This is the condition of beats. So, beats will be produced and the traveler will listen to beats. Option (2) is the correct answer.
Let the two waves produced due to the two sirens have frequency and velocity as $\nu_1, v_1$ and $\nu_2, v_2$
Since, both are sound waves, we have $v_1=v_2=v$
For one wave the traveler is moving towards the source,
$\therefore \nu^{\prime}=\nu\left(\frac{v-v_o}{v}\right)$
For the other the traveler is moving away from the source
$\therefore \nu^{\prime}=\nu\left(\frac{v+v_o}{v}\right)$
Seeing this, we can conclude that the waves are in phase with each other and are fluctuating repeatedly.
Since, they are sound waves they are periodic in nature. Hence, we got two waves that are periodic and are repeatedly fluctuating. This is the condition of beats. So, beats will be produced and the traveler will listen to beats. Option (2) is the correct answer.
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