Physics > Capacitors > 7.0 Mechanical force on the charged conductor
Capacitors
1.0 Introduction
2.0 Different types of capacitors and its capacitance.
3.0 Parallel Plate Capacitor
3.1 When equal and opposite charges placed on plates
3.2 When unequal charges are placed on the two plates
4.0 Capacitance of spherical conductor
5.0 Capacitance of a earthed sphere by a concentric spherical shell
6.0 Capacitance of a cylindrical capacitor
7.0 Mechanical force on the charged conductor
8.0 Redistribution of Charge
9.0 Dielectrics (Insulators) and Polarization
9.1 Effect of Dielectric
9.2 Capacitance of a Capacitor Partially Filled with Dielectric
9.3 Quantities after inserting dielectric in a capacitor (fully)
10.0 Combination of capacitors
11.0 Energy Density ($u$)
12.0 $R$-$C$ Circuits
13.0 Method of Finding Equivalent Capacitance
14.0 Some important concepts
15.0 Van De Graaff Generator
7.1 Force between the Plates of a Capacitor
3.2 When unequal charges are placed on the two plates
9.2 Capacitance of a Capacitor Partially Filled with Dielectric
9.3 Quantities after inserting dielectric in a capacitor (fully)
Consider a parallel plate capacitor with plate area $A$. Suppose a positive charge $q$ is given to one plate and a negative charge $-q$ to the other plate. The electric field on the negative plate due to positive charge $$E = \frac{\sigma }{{2{\varepsilon _ \circ }}} = \frac{q}{{2A{\varepsilon _ \circ }}}$$
The magnitude of force on the charge in negative plate is $$F = qE = \frac{{{q^2}}}{{2A{\varepsilon _ \circ }}}$$
This is the force with which both the plates attract each other. Thus,$$F = \frac{{{q^2}}}{{2A{\varepsilon _ \circ }}}$$
