+84 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?
+15054 How many milliamps of current will I measure?
\(R=\frac{U}{I}=\frac{500V}{0.025A}\\ R=20k\Omega\)
The parallel-connected wire halves offer a quarter of the resistance of the original wire.
\(I=\frac{U}{R}=\frac{175V}{5k\Omega}=0,035A\\ \color{blue}I=35mA\)
We measure 35mA.
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