i = 12.5(1-e-t/CR)
Current = i
Resistance = R
Capacitance = C
Time = t
Firstly i had to calculate the current flowing after 0.5s, given a 30k[tex]\Omega[/tex] resistance and a 20µF capacitance.. easily done.
Then i had to work out how long it took to reach 10A, so rearranging the formula with natural logs right? So rearranging to work out t.
2. The attempt at a solution
I've done it three times now (different each time just incase i made a stupid error) but forgot to bring my paper work with me but both times I've ended up with a -t and when i put in the numbers it doesnt equal what i'm expecting or the calculator comes up with a math error, from trial and error i'm expecting 966ms or 0.966s. I've done the previous question in which just had letters, so i tried transposing the groups of numbers for letters then working it out after aswell but that didnt work either!