Animate
Play the applet in order to plot the magnetic field along the axis of a pair of Helmholtz coils as a function of the distance from the axis midpoint. The red and blue lines are the fields of the individual coils. The green line is the net field. (Note that the value of Time is the same as x in meters.
Click Show graph to see first and second derivatives of the net field. (The y-axis units are arbitrary.)
B'(x)--orange line
B''(x)--magenta line