Answer:
I=9.6×e^{-8} A
Step-by-step explanation:
The magnetic field inside the solenoid. 
B=I*500*muy0/0.3=2.1×e ^-3×I. 
so the total flux go through the square loop. 
B×π×r^2=I×2.1×e^-3π×0.025^2
=4.11×e^-6×I 
we have that 
(flux)'= -U 
so differentiating flux we get 
so the inducted emf in the loop. 
U=4.11×e^{-6}×dI/dt=4.11×e^-6×0.7=2.9×e^-6 (V) 
so, I=2.9×e^{-6}÷30
I=9.6×e^{-8} A