# Measuring permittivity of free space physics

Theory The capacitance is a measure of the ability of the capacitor to store charges when current passes through its terminals.

For small separations the discharge of the sphere was too quick and so reliable force meter readings could not be obtained. University Physics with Modern Physics. The force was recorded, for different separations, and this was used to calculate? In this lab report, the value of permittivity of free space is determined using the relationship between capacitance and plate separation distance. By adjusting a force meter so that it agreed exactly with the calculated value, a meter can be calibrated. We also attempted to determine the accuracy of the force meter. This was done by measuring the force between a charged sphere and an earthed metal plate. Possible causes for this could be vibrations in the laboratory as people moved around or the effects of other electrical equipment in the room. The plate acts as a mirror and so the system behaves identically to having two oppositely charged spheres. A possible way of reducing this error would be to damp the stand on which the force meter was held. This was done by measuring the force between a charged sphere and an earthed metal plate as a function of separation and of the charge. Before charging the sphere it was first placed in the force meter.

Despite this, accurately measuring the electric constant is still important because it allows for the confirmation of theory by comparison of theoretical and experimental determinations of the constant.

This was done by measuring the force between a charged sphere and an earthed metal plate.

The force meter and sphere were then lowered to approximately the maximum height of the adjustable stand. University Physics with Modern Physics. The readings given by the mass balance were seen to be far more stable and consistently lower than the readings from the force meter.

It follows therefore that there must have been errors in our experimental procedure beyond the uncertainties of the measurement devices. Possible causes for this could be vibrations in the laboratory as people moved around or the effects of other electrical equipment in the room.

The charge on the sphere was then measured using an electrostatic amplifier both before and after the force reading were taken.

There are a number of potential sources of this error.

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