What value of current needs to be passed through this coil

Question

1) A steel toroid of the dimensions shown in Fig. 1 is wound with a 500 turn coil of wire. What value of current needs to be passed through this coil in order to produce a flux of 250 μ Wb in the toroid, if under these conditions the relative permeability of the toroid is 300.

2) For the circuit in fig 2, i(t) = 4(2- e^-10t)mA. If i₂(0) = -1mA, find

(a) i₁ (0)
(b) v(t), v1(t) and v₂(t)
(c) i₁(t) and i₂(t)