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The length of two open organ pipes are l...

The length of two open organ pipes are `l` and `(l+deltal)` respectively. Neglecting end correction, the frequency of beats between them will be approximately

A

`(v)/(2l)`

B

`(v)/(4l)`

C

`(vDelta l)/(2l^(2))`

D

`(vDelta l)/(l)`

Text Solution

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The correct Answer is:
To find the frequency of beats between two open organ pipes of lengths \( l \) and \( l + \Delta l \), we can follow these steps: ### Step 1: Understand the fundamental frequency of an open organ pipe The fundamental frequency \( f \) of an open organ pipe is given by the formula: \[ f = \frac{v}{2L} \] where \( v \) is the speed of sound in air and \( L \) is the length of the pipe. ### Step 2: Calculate the frequency of each pipe For the first pipe of length \( l \): \[ f_1 = \frac{v}{2l} \] For the second pipe of length \( l + \Delta l \): \[ f_2 = \frac{v}{2(l + \Delta l)} \] ### Step 3: Determine the beat frequency The beat frequency \( f_{beat} \) is the absolute difference between the two frequencies: \[ f_{beat} = |f_1 - f_2| \] Substituting the expressions for \( f_1 \) and \( f_2 \): \[ f_{beat} = \left| \frac{v}{2l} - \frac{v}{2(l + \Delta l)} \right| \] ### Step 4: Simplify the expression Factor out \( \frac{v}{2} \): \[ f_{beat} = \frac{v}{2} \left| \frac{1}{l} - \frac{1}{l + \Delta l} \right| \] ### Step 5: Find a common denominator The common denominator for the fractions is \( l(l + \Delta l) \): \[ f_{beat} = \frac{v}{2} \left| \frac{(l + \Delta l) - l}{l(l + \Delta l)} \right| \] This simplifies to: \[ f_{beat} = \frac{v}{2} \left| \frac{\Delta l}{l(l + \Delta l)} \right| \] ### Step 6: Approximate for small \( \Delta l \) If \( \Delta l \) is small compared to \( l \), we can approximate \( l + \Delta l \approx l \): \[ f_{beat} \approx \frac{v}{2} \cdot \frac{\Delta l}{l^2} \] ### Final Result Thus, the frequency of beats between the two open organ pipes is approximately: \[ f_{beat} \approx \frac{v \Delta l}{2l^2} \] ---

To find the frequency of beats between two open organ pipes of lengths \( l \) and \( l + \Delta l \), we can follow these steps: ### Step 1: Understand the fundamental frequency of an open organ pipe The fundamental frequency \( f \) of an open organ pipe is given by the formula: \[ f = \frac{v}{2L} \] where \( v \) is the speed of sound in air and \( L \) is the length of the pipe. ...
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Knowledge Check

  • The lengths of two organ pipes open at both ends are L and L + d . If they are sounde together, then the beat frequency will be

    A
    `(2Vd)/(L(L+x))`
    B
    `(2Vd)/(L(L+d))`
    C
    `(2L(L+d))/(Vd)`
    D
    `(Vd)/(2L(L+d))`
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    A
    2
    B
    6
    C
    8
    D
    7
  • Two closed organ pipes have lengths L and L+X . When two pipes are sounded together , the beat frequency is

    A
    `(vx)/(4L(L+x))`
    B
    `(vx)/(4L(L-x))`
    C
    `(4L(L+x))/(vx)`
    D
    `(2L(L-x))/(vx)`
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