Three resistors of 10 ohm, 25 ohm, and 15 ohm are connected in parallel across a 3 V battery. What is the equivalent resistance of the combination?
A50 ohm
B16.7 ohm
C1.5 ohm
D4.84 ohm
Answer & Solution
Correct answer: D. 4.84 ohm
1. For resistors in parallel, the equivalent resistance satisfies 1/R_equiv = 1/R1 + 1/R2 + 1/R3.
2. Substitute the values: 1/R_equiv = 1/10 ohm + 1/25 ohm + 1/15 ohm.
3. This sum equals approximately 0.2067 per ohm.
4. R_equiv = 1 / 0.2067 per ohm, which is approximately 4.84 ohm.
5. 50 ohm would result from mistakenly adding the resistances directly, as if they were in series.
_Source: OpenStax Physics (CC BY 4.0), Ch 19 "Electrical Circuits", section Find the Current through Parallel Resistors_
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