An indirect measurement of the speed of light in a General Physics Laboratory

摘要

This paper features an indirect method to measure the speed of light. First, the electrical permittivity of air ε0, is obtained, by using a capacitance meter to measure the capacitance of a parallel-plate capacitor, by varying the separation between its plates. By means of a least squares adjustment, the slope of the straight line is calculated which is related to ε0.Next, the magnetic permittivity of air μ0is obtained by using a solenoid through which different currents are circulated and the magnetic field is measured in its centre using the Hall sensor of a Smartphone. By means of a least squares adjustment, the slope of the straight line is calculated which is related to μ0.Once ε0and μ0have been obtained, the speed of light is calculated by the expressionc=1ε0μ0with its corresponding absolute and relative errors, to verify if the obtained value is compatible with the exact value ofc.