Example: An insulating solid sphere of radius a has a uniform volume charge density p and carries a total positive charge Q. (A) Calculate the magnitude of the electric field at a point outside the sphere. (B) Find the magnitude of the electric field at a point inside the sphere. Solution: A) Because the charge distribution is spherically symmetric, we again select a spherical gaussian surface of radius r, concentric with the sphere, as shown in Figure 1.16. E = k, forr >a

Q1. a) () Describe in words how you might apply Gauss's law to a closed surface to determine the free charge enclosed. Describe the two most useful Gaussian surfaces. Where are they used and what differences must be accounted for when applying them? (ii)

Q1. a) (i) Describe in words how Gauss's law is applied to determine the free charge on an arbitrarily shaped metal surface. (ii) Describe the two most useful Gaussian surfaces. Where are they used and what differences must be accounted for when applying them?

1. Uniform electric and magnetic fields are oriented at right angles and perpendicular to each other. An electron moves at right angles to both the fields and passes undeflected through the field. If the magnitude of the electric filed intensity is 2000 V/m, determine the value of magnetic flux density and magnetic field intensity (assume free space conditions).