What happens to electric fields in the presence of dielectrics?

In the presence of dielectrics, electric fields are reduced due to the polarisation of the dielectric material.

When an electric field is applied to a dielectric material, the positive and negative charges within the material tend to shift in opposite directions. This shift creates an induced electric field within the dielectric that opposes the applied field. This phenomenon is known as polarisation. The net effect is a reduction in the overall electric field within the dielectric.

The degree of polarisation, and thus the reduction in the electric field, depends on the nature of the dielectric material. This is quantified by a property known as the relative permittivity or dielectric constant of the material. The higher the dielectric constant, the greater the polarisation and the more the electric field is reduced.

The presence of a dielectric also affects the capacitance of a capacitor. When a dielectric is inserted between the plates of a capacitor, the capacitance increases. This is because the reduced electric field allows more charge to be stored on the plates for a given potential difference. The factor by which the capacitance increases is equal to the dielectric constant of the material.

In summary, the presence of a dielectric in an electric field leads to polarisation of the material, which in turn reduces the electric field. The degree of reduction depends on the dielectric constant of the material. This has important implications for the operation of capacitors and other electronic devices.