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.
Magnetic fields. 1  Electric fields arise from voltage. 2  Their strength is measured in Volts per metre (V/m) 3  An electric field can be present even when a device is switched off.  Field strength decreases with distance from the 1  source. Most building materials shield electric fields to some extent.  Magnetic fields arise from current flows.