Question about induced electric fields. The long solenoid in Fig.a has 500 turns per meter and cross-sectional area of 4.0 cm². The current in its windings is increasing at 100A/s.

1. What is the magnitude of the induced emf in the wire loop outside the solenoid?

2. What is the  magnitude of the induced electric field within the loop if its radius is 2.0 cm.

Figure: long solenoid carrying a current I that is increasing at a rate dI/dt.  The magnetic flux in the solenoid is increasing at a rate dΦ_B/dt and this changing flux passes through a wire loop. An emf = -dΦ_B/dt is induced in the loop, inducing a current I' that is measured by the galvanometer G.

(a) I, dl dt Galvanometer Wire loop G I' Solenoid 1, di dt Blue cylinder shows region with magnetic field B.