The figure shows a fiveturn 10cmdiameter coil with R 018 Oh

The figure shows a five-turn, 1.0-cm-diameter coil with R = 0.18 Ohm inside a 2.0-cm-diameter solenoid. The solenoid is 9.0 cm long, has 130 turns, and carries the current shown in the graph. A positive current is cw when seen from the left. Determine the current in the coil at t = 0.010s. Express your answer using two significant figures.

Solution

dI / dt = 0.5/0.01 = 50 A/s

I_coil = [ N_coil * mu₀ * n * pi * r²_coil / R_coil ] * [dI_sol / dt]

= [ 5 * 4 pi * 10^-7 * 130 * pi * (0.5 * 10^-2)² / 0.09 * 0.18] * [50]

= 0.000198 A