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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 \$500\$ volts through this wire and measure \$25\$ milliamps of current.  If I cut the wire in half and pass \$175\$ volts through it, how many milliamps of current will I measure?

Nov 2, 2023

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If we cut the wire in half, the resistance will also be halved. Therefore, the new resistance will be R/2.

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

Therefore, the new current will be:

I = V/(R/2) = 2V/R

We know that the original current was 25 milliamps, so the new current will be:

I = 2V/R = 2 * 175V / (25mA * 1000) = 14mA

Therefore, the new current is 14 milliamps.

Nov 2, 2023