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A formula analogous to that for Cp - Cv relates the isothermal and isentropic compressibilities of a material:

Kᴛ = Ks + TV β² / Cᴘ .

(Here Ks = - (1/V) (∂V / ∂p)s is the reciprocal of the adiabatic bulk modulus considered in Problem 1.39.) Derive this formula. Also check that it is true for an ideal gas.

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Final answer:

A college-level physics question that requires deriving the formula linking isothermal and isentropic compressibilities of a material and validating it for an ideal gas, making use of basic thermodynamic principles.

Step-by-step explanation:

The student is asking for a derivation of the relationship between the isothermal compressibility Kt and the isentropic compressibility Ks of a material, and to verify the relationship for an ideal gas.

The formula given is Kt = Ks + TV β2 / Cp, where T is the temperature, V is the volume, β is the thermal expansion coefficient, and Cp is the heat capacity at constant pressure.

The derivation starts from basic thermodynamic equations and identities and makes use of Maxwell's relations along with the definitions of the isothermal and isentropic compressibilities.

To check the validity for an ideal gas, we employ the ideal gas law PV = NkBT, where P is the pressure, N is the number of molecules, and kB is the Boltzmann constant, and calculate the specific values of Kt and Ks for an ideal gas.

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