In this lecture we continue our discussion concerning the generation of magnetic fields from the motion of conducting fluids. We proposed the “short sudden” idealization, which led to equation (17) in the preceding lecture. Vj in that equation is the large scale, steady fluid velocity that continually shears the field. In addition we introduce quick bursts of turbulence during which any amount of rotation or twisting of the field can be accomplished. Following these quick bursts of motion the fluid is held motionless so that small scale irregularities die off and we are left with a smooth, average, large scale state. This cycle is repeated at time intervals x, producing the dynamo equations for the mean vector potential Ai (xk, t).