An annular ring with a uniform surface charge density σ sits in the xy plane, with its center at the origin of the coordinate axes. The annulus has an inner radius r1 and outer radius r2. Required:
If you can find symmetries in a physical situation, you can often greatly simplify your calculations. Find a symmetry in the annular ring before calculating the potential along the z axis through the ring's center.

The space within which a test north pole experiences a force magnetic poles 2. a powerful stream of electrons flowing high above the earth in the ionosphere electrojet 3. a concept to explain the directional nature of a magnetic field field lines 4. coil of wire designed to produce a magnetic field by a current passing through its windings ionosphere 5. that region above the earth's atmosphere where particles exist in an ionized state magnetic field 6. the extremities of a magnet where the field lines tend to converge or concentrate aurora borealis 7. a phenomenon that occurs in the northern latitudes; the northern lights solenoid