In the figure a 120turn coil of radius 26 cm and resistance

In the figure, a 120-turn coil of radius 2.6 cm and resistance 6.3 ohm is coaxial with a solenoid of 220 turns/cm and diameter 4.5 cm. The solenoid current drops from 1.5 A to zero in time interval Delta t = 25 ms. What current is induced in amperes in the coil during Delta t? Number__________Units

Solution

magnetic field inside solenoid when current is1.5 A=uni=0.0414

For coil change in flux per unit time gives induced emf

change in flux=120*0.0414*area of solenoid=7.9*10^(-3)

change in flux per unit time=induced emf =0.316

current=induced emf/resistance=0.05 A