A search coil in an AC generator is rotated at a constant frequency f f\,f in a uniform magnetic field. At time t1t_1t1, the magnetic flux linking the coil is at its maximum positive value. At time t2t_2t2, the induced electromotive force (emf) in the coil is at its maximum positive value.
What is the smallest positive value of t1−t2t_1 - t_2t1−t2?
14f\frac{1}{4f}4f1
12f\frac{1}{2f}2f1
34f\frac{3}{4f}4f3
18f\frac{1}{8f}8f1