If a branch is removed from a parallel circuit of three equal resistors, what happens to the total resistance?

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

Answer: (C)

In parallel circuits, the total resistance depends on how many paths there are for current to take. More parallel paths lower the overall resistance; fewer paths raise it. With three identical resistors in parallel, the equivalent resistance is one third of a single resistor. If you remove one branch, you’re left with two identical resistors in parallel, giving an equivalent resistance of one half of a single resistor. Since one-half is larger than one-third, the total resistance increases. At a fixed voltage, that means the total current decreases accordingly.