In Figs. (a) and (b), two air-cored solenoids P and Q have been shown. They are placed near each other. In Fig. (a), when Ip the current in P, changes at the rate of 5 A/s, an emf of 2 mV is induced in Q.The current in P is then switched off, and a current changing at 2 A/s is fed through Q as shown in diagram. What emf will be induced in P?