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?

onyuIee Aug 5, 2024

#1**+1 **

I = V/R

\(R_1=\frac{V_1}{I_1}=\frac{500V}{0.025A}=\color{blue}20k\Omega\)

I halve the length of the wire, hence the resistance \(R_1\).

\(I_2=\frac{V_2}{R_2}=\frac{175V}{10k\Omega}=\color{blue}17.5mA\)

I apply the voltage\(V_2\) to both halves of the wire, thus halving the resistance \(R_1\).

\(I_3=\frac{V_2}{R_3}=\frac{175V}{5k\Omega}=\color{blue}35mA\) in both wire halves together.

!

asinus Aug 6, 2024