Figure a shows a circuit consisting of an ideal battery with

Figure a shows a circuit consisting of an ideal battery with emf ? = 6.00ÂľV a resistance R, and a small wire loop of area 5.0 cm2. For the time interval t = 10 s to r = 20 s, an external magnetic field is set up throughout the loop. The field is uniform, its direction is into the page in Figure a, and the field magnitude is given by B = at, where B is in teslas, a is a constant, and t is in seconds. Figure b gives the current i in the circuit before, during, and after the external field is set up. The vertical axis scale is set by is = 2.0 mA. Find the constant a in the equation for the field magnitude.