Answer:
a) Δt = 0.437 sec. b) E = 0.4375 J.
Explanation:
a)
First we find the current with V = IR
I = V/R
I = 4/8
I = 1/2.
Now, we find the "time" with the formula:
emf = L×Δi / Δt
Δt = L×Δi / emf
Δt = 3.5×0.5 / 4
Δt = 0.437 sec.
b)
We find the energy stored in the inductor with the formula:
E = 1/2×LI^2
E = 1/2×3.5×(0.5)^2
E = 0.4375 J.