When an extra resistor is added in parallel to a circuit, the total resistance:

• A. It will decrease
• B. It will increase
• C. It will stay the same
• D. It will double

Answer: (A)

In a parallel arrangement, each resistor provides a separate path for current while the voltage across every path is the same. The total resistance adds as the reciprocal: 1/R_total = 1/R1 + 1/R2 + ... When you add another resistor in parallel, you add another term to that sum, which increases the total of the reciprocals. That makes R_total smaller, since you’re taking the reciprocal of a larger number.

A quick intuition: two identical resistors in parallel give half the resistance of one, showing that adding a parallel path reduces the overall resistance. The total will decrease for finite, non-infinite resistances. The only time it wouldn’t change is if the new path has infinite resistance (an open circuit), which effectively doesn’t add a path.