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The current in an inductor when energy is stored. Please help

by BryceHarper
Tags: current, electronics, energy, inductor, physics
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BryceHarper
#1
Nov25-12, 04:11 PM
P: 15
1. The problem statement, all variables and given/known data

What's the current in a 15mH inductor when the stored energy is 42μJ

2. Relevant equations

E = 1/2 L i^2

3. The attempt at a solution

.000042J = (.5)(.015H)(i^2)
.000042J = (.0075)(i^2)
.0056 = i^2
√ (.0056) = i
.0748331 = i

I need to put the answer in with only two sig figs so i put in .07 but it was wrong
What am I doing wrong?
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tiny-tim
#2
Nov25-12, 05:16 PM
Sci Advisor
HW Helper
Thanks
tiny-tim's Avatar
P: 26,157
Hi BryceHarper!
Quote Quote by BryceHarper View Post
I need to put the answer in with only two sig figs so i put in .07 but it was wrong
.07 is two decimal places but only one significant figure
BryceHarper
#3
Nov25-12, 05:37 PM
P: 15
I'm dumb haha. Thanks!


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