How does a parallel circuit change when a branch is added?

1. The total resistance increases, so the current in the circuit decreases.

2. The total resistance decreases, so the current in the circuit increases.

3. The total resistance increases, so bulbs shine at a lower brightness.

4. The total resistance decreases, so bulbs shine at a higher brightness.

When a branch is added, the current from the power supply then has

one more choice of path to follow to return to the power supply. On the

whole, then, it becomes easier for current to travel the full circuit, that's

equivalent to saying that the total resistance has decreased, and so the

total current increases.

If the power supply is able to deliver the increased demand, then the bulbs

in the existing branches are unaware of the change, and their brightness

doesn't change.

Choice-2 is the only choice that isn't at least partly wrong.