Hello, The question goes like this: A long solenoid has n turns per unit length and carries a current given by I=I₀sinωt. The solenoid has a circular cross section of radius R. Find the induced electric field at a radios r from the axis of the solenoid for (a) r<R (b) r>R Well, i got the first part as E=μR²N²ωI₀cos(ωt)/(2Rl). Does this looks like it? For the second bit, i found it as zero. But i am not really sure. And if it is zero, What should i say?