Calculate emf The magnitude of the magnetic field encircled by a single loop of wire. $12 \mathrm{~cm}$ in radius and of $8.5 \Omega$ resistance, changes with time as shown in Fig. 31-30. Calculate the magnitude of the emf in the loop as a function of time. Con- FIGURE $31-30=$ Problem 4 sider the time intervals (a) $t_{1}=$ $0.0 \mathrm{~s}$ to $t_{2}=2.0 \mathrm{~s},(\mathrm{~b}) t_{2}=2.0 \mathrm{~s}$ to $t_{3}=4.0 \mathrm{~s},(\mathrm{c}) t_{3}=4.0 \mathrm{~s}$ to $t_{4}=6.0 \mathrm{~s}$
The (uniform) magnetic field is perpendicular to the plane of the loop.