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.
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