Changing equivalent resistance changes the source current
The mistake
Adding a parallel branch but keeping total current fixed.
Why it feels right
The battery voltage is fixed, so the current can feel fixed too.
How to catch it
You add a resistor in parallel and do not update current drawn from the battery.
The first principle
For an ideal voltage source, I_total = V/R_eq. Adding a parallel branch lowers R_eq, so total source current increases.
worked mini-example
A second identical bulb is added in parallel to one bulb on a battery. What happens to total current?
Common wrong move
It stays the same and splits.
Correct
It doubles for ideal identical bulbs; each branch still gets battery voltage.
Test the repair CIR-08 · transfer
Make a fresh prediction before referring to the worked example.