The smaller the angle α, the lower the induced emf. Polarity of the emf is opposite that in (a) and is shown in
Figure 10.4b. Note that E ¼ v B points from the negative to the positive ends in the bar. This may seem strange at
first, but we must remember that this is the field on a positive charge (electrons move in the direction opposite the
electric field). The external field (such as in a circuit) will point from positive to negative as required (see Figure 10.4c).