1. The problem statement, all variables and given/known data A coil with 140 turns, a radius of 5.2 cm, and a resistance of 11.0 Ω surrounds a solenoid with 200 turns/cm and a radius of 4.5 cm. The current in the solenoid changes at a constant rate from 0 A to 2.0 A in 0.10 s. Calculate the magnitude and direction of the induced current in the 140-coil. 2. Relevant equations EMF = -N (dφ/dt) 3. The attempt at a solution Iind = EMF/ R of the coil, due to Ohm's law. So I know that I should find the EMF of the coil using EMF = -N (dφ/dt) = -N (A) (dB/ dt) I should find dB/dt, but I'm not totally sure how. I think I could use the magnetic field formula for a ring at the center maybe B= (μ0I) / (2 rcoil) , where the current, I , is changing due to the solenoid?