(a)
The number of modes with wavelength between
(a)
Answer to Problem 7P
The number of modes with wavelength between
Explanation of Solution
Write the expression for the number of modes of vibration of waves which is confined by a cavity that is related to wavelength and length of the string is,
Here,
Re-write the expression (I),
Write the number of modes with wavelength between
Here,
Conclusion:
Substitute
Thus the number of modes with wavelength between
(b)
The number of modes per unit wavelength per unit length.
(b)
Answer to Problem 7P
The number of modes per unit wavelength per unit length is
Explanation of Solution
Write the expression the number of modes per unit wavelength per unit length,
Here,
Conclusion:
Substitute
The number of modes per unit wavelength per unit length is
(c)
The expression obtained the same value as found in sub part (a).
(c)
Answer to Problem 7P
The expression obtained the same value as found in sub part (a) that is the number of modes with wavelength between
Explanation of Solution
Write the expression the number of modes is,
Here,
Re-write the expression (I) by differentiating the term, for the number of modes per unit wavelength per unit length of the string,
Re-write the expression (II) for number of modes,
Conclusion:
Substitute
The expression obtained the same value as found in sub part (a) that is the number of modes with wavelength between
(d)
The reason to justify replacing
(d)
Answer to Problem 7P
For the shorter wavelengths
Explanation of Solution
Write the expression the number of modes per unit wavelength per unit length,
Here,
Considering
Conclusion:
For the shorter wavelengths
And also for the shorter wavelengths
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Chapter 3 Solutions
Modern Physics
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