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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 250 volts through it, how many milliamps of current will I measure?

 Mar 15, 2020
 #1
avatar+23566 
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If you put 250 volts ACROSS the wire (you don't put voltage THROUGH a wire) the curent woud increase through the wire

250/50=  by 5 times       5 x 200 ma = 1 amp 

 

EDIT:::::  

BUT   you cut the wire in half....this cuts the resistance in HALF

    cutting the resistance in half will DOUBLE the current through the wire

          1 amp x 2 = 2 amps   = 2000 millimps

 Mar 15, 2020
edited by ElectricPavlov  Mar 15, 2020
 #2
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i just checked and its wrong

 Mar 15, 2020
 #3
avatar+23566 
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It is not incorrect      1 amp = 1000 milliamps  ,   silly !

ElectricPavlov  Mar 15, 2020
edited by ElectricPavlov  Mar 15, 2020
 #5
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Actually, it is wrong, EP.

The voltage increased five (5) times, and because the wire is now half as long, the resistance is now 125 ohms

or (1/2 * 250) ohms. This means (2) amps or (2000) miliamps of current now pass through the wire. 

 

GA

GingerAle  Mar 15, 2020
edited by GingerAle  Mar 16, 2020
 #6
avatar+23566 
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Thanx GA....missed the 1/2 as long part  !!!!!  

I apologize !!!!!

 

 

the voltage increased 5 times   and the resistance is cut in half    so the current will increase   5 x 2 times

10 x 200 = 2000 mamps   

 

 

D'Oh !  

ElectricPavlov  Mar 15, 2020
edited by ElectricPavlov  Mar 15, 2020
 #4
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i know! that's what i entered lol and it was marked wrong

 Mar 15, 2020

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