If your equation is in vertex form, then the axis of is: x= h in the general vertex form equation y = (x-h)2 + k. If your equation is in standard form, then the formula for the axis of symmetry is: $$ x = \frac {-b}{ 2a} $$ from the general standard form equation $$ y = ax^2 +bx + c $$.
Lesson Summary. All magnetic fields are created by moving charged particles. Stationary charged particles do not generate magnetic fields. An electromagnet is a magnet that relies on an electric current to produce the magnetic field. The simplest electromagnet is simply a wire carrying a current, which generates a magnetic field all around the wire.
Even the magnetic field produced by a current-carrying wire must form complete loops. Above, you were told that a loop of current-carrying wire produces a magnetic field along the axis of the wire. The right-hand rule gives the direction of the field inside the loop of wire. The magnetic field turns back the other way outside of the loop. As shown in the figure on the right, this magnetic field from a loop of current-carrying wire looks similar to the field from a permanent bar magnet.