An insulated copper wire of 100 turns is wrapped around a wooden cylindrical core of the crosssectional area $24 \mathrm{~cm}^2$. The two ends of the wire are connected to a resistor. The total resistance in the circuit is $12 \Omega$. If an externally applied uniform magnetic field in the core along its axis changes from 1.5 T in one direction to 1.5 T in the opposite direction, the charge flowing through a point in the circuit during the change of maqnetic field will be mC.