1. Applications of Gauss’s Law

2. When is Gauss’s Law Useful?

3. Sphere of Charge

4. Concentric Cavity Let’s say we have a sphere with a concentric cavity.
The charge is not in the cavity only in the “donut shape”
Draw a sphere big radius b, small radius a.
If charge is positive then we expect the charge to be directed towards the centre.
Everywhere inside the cavity E =0
If we take a Gaussian surface so b>r>a
So if we’re outside the shell, it acts as a point charge at the centre of the shell.

5. Radius Dependent Charge Density

6. Homework Do the sheet please  Due in 4th February
Read p676 to end of chapter