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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 = 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 300 milliamps of current. If I cut the wire in half and pass 800 volts through it, how many milliamps of current will I measure?

 Jan 25, 2021
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We place 50 volts across this wire and measure 300 milliamps of current THROUGH the wire  

                                                                       (Voltage does not go THROUGH a wire....current does)

 

V = IR          50 = .3 (R)      R = 166 2/3 ohms           (300 mAmps =  . 3 Amps )

 

Cut wire in half    R2 becomes 1/2 original   :        1/2 (166 2/3) = 83 1/3 ohms

 

WIth 800 V applied:

  V    =   IR

800  =   I *   83 1/3     I = 800/(83 1/3 )   = 9.6 amps     which is 9600 mAmps

 Jan 25, 2021

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