Parallel Resistors Equivalent Resistance

Steps:

• For resistors in parallel, the total current divides between branches while voltage remains the same across both.
• Apply the reciprocal formula: 1/Req = 1/R1 + 1/R2.
• Combine fractions: 1/Req = (R2 + R1)/(R1 R2).
• Invert to find Req: Req = (R1 R2)/(R1 + R2).

Why B is correct:

• B matches the standard parallel resistance formula, derived from Kirchhoff's current law, where equivalent resistance is the product divided by the sum.

Why the others are wrong:

• A is the formula for series connection, not parallel.
• C inverts the parallel formula, yielding conductance instead of resistance.
• D multiplies resistances without accounting for parallel current division.

Final answer: B