When a train approaches a stationary observer, the apparent frequency of the whistle is n ′ and when the same train recedes away from the observer, the apparent frequency is n ′ ′ . The apparent frequency n , when the observer moves with th

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When a train approaches a stationary observer, the apparent frequency of the whistle is n ′ and when the same train recedes away from the observer, the apparent frequency is n ′ ′ . The apparent frequency n , when the observer moves with the train is

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Correct answer: C. n = 2 n ′ n ′ ′ n ′ + n ′ ′

n ′ = v n v - v s , n ′ ′ = v n v + v s ∴ n n ′ = 1 - v s v , n n ′ ′ = 1 + v s v Adding the two, we get n n ′ + n n ′ ′ = 2 ∴ n = 2 n ′ n ′ ′ n ′ + n ′ ′

When a train approaches a stationary observer, the apparent frequency of the whistle is n ′ and when the same train recedes away from the observer, the apparent frequency is n ′ ′ . The apparent frequency n , when the observer moves with the train is

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