In a parallel combination of resistors, removing one branch causes the equivalent resistance to do what?

• A. It decreases
• B. It increases
• C. It stays the same
• D. It becomes zero

Answer: (B)

In a parallel circuit, the branches add up the conductances (1/R). This means more paths for current lower the total resistance. When you remove one branch, you lose one of those paths, so the total conductance decreases and the reciprocal 1/R_eq becomes smaller. As a result, the equivalent resistance R_eq increases.

For example, two 100-ohm resistors in parallel give an equivalent of 50 ohms. If one branch is removed, you’re left with a single 100-ohm resistor, so the equivalent resistance rises to 100 ohms. Therefore, removing a branch in a parallel set increases the overall resistance.