計算題(每題二十五分)
An electric field is directed out of the page within a circular region of radius R=3.00 cm. The magnitude of the electric field is given by E = (0.500 V/m·s)(1-r/R)t, where t is in seconds and r is the radial distance (r ≤ R). What is the magnitude of the induced magnetic field at radial distance (a) 2.00 cm and (b) 5.00 cm?