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Expert: - 3/31/2008


Question
using the equation:
I = 0.8[1-10^(-0.0434t)] after ,t, sec
a) what is the current after 5 s
b) rewrite the equation for , I, solving for t.
c) use the equation from part b. to determine the time it takes for the current to reach 0.5A

I am having trouble on b. your help would be greatly appreciated. Thanks in advance

Answer
Questioner:   khaleel
Category:  Advanced Math
Private:  No
 
Subject:  equations
Question:  using the equation:
I = 0.8[1-10^(-0.0434t)] after ,t, sec
a) what is the current after 5 s
b) rewrite the equation for , I, solving for t.
c) use the equation from part b. to determine the time it takes for the current to reach 0.5A

I am having trouble on b. your help would be greatly appreciated. Thanks in advance
..............................................
Hi, Khaleel,

If that's all you need, then:

I = 0.8[1-10^(-0.0434t)]

I = (4/5)[1-10^(-0.0434t)]

5I/4 = 1-10^(-0.0434t)

10^(-0.0434t) = 1 - 5I/4

-0.0434t = log(1 - 5I/4)

t = log(1 - 5I/4)/(-0.0434)

t = - log(1 - 5I/4)/0.0434

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