John N. Fox

Measurement of the transition temperature of a high Tc superconductor

The transition temperature of a ceramic superconductor, Y1Ba2Cu3O7−x, is determined using a tunnel diode oscillator.

Experiments using a tunnel diode oscillator

A description is given of an apparatus suitable for measuring magnetic susceptibility in the undergraduate laboratory. Several applications are considered in detail, and extension of the technique to nonmagnetic studies is briefly discussed.

Absorption of sound in helium vapor

We have studied the absorption of sound in helium vapor using a broad band heat pulse technique. The results are in good accord with classical hydrodynamics and with experimental values of the viscosity and thermal conductivity.

Measurement of thermal expansion coefficients using a strain gauge

A strain gauge is employed to determine the coefficient of thermal expansion of a solid. The apparatus is interfaced to a computer to obtain a linear plot of displacement against temperature.

A study of the phase transition of a ferromagnetic material

The Curie temperature is determined from a resistivity measurement of a nickel sample, and the result is compared to that obtained from a method previously described in this Journal. In addition, the Curie temperature is determined for nickel and Monel 400 using a tunnel diode oscillator. Data analysis includes a method to calculate a critical point exponent.

Measurement of the thermal properties of a metal using a relaxation method

An undergraduate experiment is described which employs a relaxation method for the measurement of the thermal conductivity and specific heat of a metallic sample in the temperature range 0–100°C.

A real‐time demonstration of the depth dependence of pressure in a liquid

A demonstration experiment is described that employs a computer interface to make a real‐time plot of the pressure in a liquid as a function of depth. When two immiscible fluids are used the change in density across the fluid interface can be demonstrated. Data are presented for the case of water floating on carbon tetrachloride.

Shape analysis of pulsed second sound in crystalline4He

AbstractWe have observed that second-sound pulses in crystalline4He contain features corresponding to the input pulse power densityp(t) as well as to its time derivative,

Measurement of the vapour pressure curve of water

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