Investigating the capacitance of a parallel-plate capacitor using a reed switch
To investigate the factors which affect the capacitance of a parallel-plate capacitor using a reed switch
Battery box with 4 cells
Resistance substitution box
Through the series of experiments, we would like to verify the following theories
- Charge and Applied Potential Difference
With the increase of voltage supplied by battery, the current is increased. Moreover, in a V-I graph, the slope m is the proportional constant fC. As we can obtain the generate our desired frequency f by a signal generator, we can obtain the capacitance. .
- Effect of Plate Separation and Area of Overlap
If the capacitor is charged up by voltage V, the charge density of the capacitor plates is given by
The electric field inside the plates is given by
With the increase of plate separation, the capacitance is decreased. As Q= CV, with constant voltage supply, the number of charges stored is decreased.