Define capacitance in words.
An isolated metal sphere of radius $r$ is charged so that its potential is $V$ and the charge on it is $q$. The charge can be treated as if it were a point charge at the centre of the sphere. State an expression, in terms of $r$ and $q$, for the sphere’s potential $V$.
This isolated sphere has capacitance. Use your answers in (a) and (b)(i) to show that the capacitance of the sphere is proportional to its radius.
The sphere in (b) has a capacitance of $6.8 \, \text{pF}$ and is charged to a potential of $220 \, \text{V}$. Calculate the radius of the sphere.
An isolated metal sphere of radius $r$ is charged so that its potential is $V$ and the charge on it is $q$. The charge can be treated as if it were a point charge at the centre of the sphere.
The sphere in (b) has a capacitance of $6.8\,\text{pF}$ and is charged to a potential of $220\,\text{V}$. Calculate
the charge, in coulomb, on the sphere.
A second uncharged metal sphere is brought up to the sphere in (c) so that they touch. The combined capacitance of the two spheres is $18\,\text{pF}$. Calculate
the potential of the two spheres.
the change in the total energy stored on the spheres when they touch.