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# Another problem :>

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In physics, Ohm's law says that current through a wire, $I$, is directly proportional to voltage, $V$, and inversely proportional to resistance, $R$:

$I=\frac{V}{R}.$

It's also true that resistance is directly proportional to the length of the wire. We have a piece of wire. We pass $50$ volts through this wire and measure $200$ milliamps of current. If I cut the wire in half and pass $300$ volts through it, how many milliamps of current will I measure?

Jun 10, 2021

#1
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You will measure 200*300/50 = 1200 milliamps.

Jun 10, 2021
#2
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Re-arranging:

V/I = R

50 v / .2 A   = 250 ohms

Now cut wire in half     it i s now   125 ohms

apply 300 v across it     (NOTE: the question erroneously says  ' 300 volts THROUGH it ' )

I  =  v/R = 300/125 = 1.2 Amps     or  1200 milliamps

Jun 10, 2021
#3
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I tried 1200 milliamps, and it counted it wrong.
angelxbobaa  Jun 14, 2021
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I don't understand electricity.  This is based solely on the info given.

$$I=\frac{V}{R}\\ R\propto L\\ I=\frac{V}{kL}\\ find\;\;k\\ When \;\;V=50\;\;I=200,\;\;L=2\\ 200=\frac{50}{2k}\\ k=0.125\\so\\ I=\frac{V}{0.125L}\\~\\ Find\; I\;\;when\;V=300\;and\;L=1\\ I=\frac{300}{0.125*1}\\ I=2400\;milliamps$$

LaTex:

I=\frac{V}{R}\\
R\propto L\\
I=\frac{V}{kL}\\
find\;\;k\\
When \;\;V=50\;\;I=200,\;\;L=2\\
200=\frac{50}{2k}\\
k=0.125\\so\\
I=\frac{V}{0.125L}\\~\\
Find\; I\;\;when\;V=300\;and\;L=1\\
I=\frac{300}{0.125*1}\\
I=2400\;milliamps

Jun 15, 2021
edited by Melody  Jun 15, 2021