In the ac generator of Fig. 20.6, the emf produced is (t) = w BA sin w

In the ac generator of Fig. 20.6, the emf produced is ℰ(t) = w BA sin w t. If the generator is connected to a load of resistance R, then the current that flows is
I(t) = ωBA/R sin ωt
(a) Find the magnetic forces on sides 2 and 4 at the instant shown in Fig. 20.7. (Remember that q = wt.)
(b) Why do the magnetic forces on sides 1 and 3 not cause a torque about the axis of rotation?
(c) From the magnetic forces found in (a), calculate the torque on the loop about its axis of rotation at the instant shown in Fig. 20.7.
(d) In the absence of other torques, would the magnetic torque make the loop increase or decrease its angular velocity? Explain.