An 18 ohm and a 15 ohm resistor are connected in parallel; a 36 ohm resistor is connected in series with this combination; a 22 ohm resistor is connected in parallel with this total combination. The total current is 5 A. What current is flowing in the 15 ohm resistor?
• Parallel vs. series circuits and how voltage/current behave in each • Equivalent resistance of parallel combinations using reciprocal formula • Using Ohm’s Law (V = I·R) to find voltage across branches and current in one branch
• First, what is the total equivalent resistance of the two resistors in parallel (18 Ω and 15 Ω)? • Once you know that, what is the total resistance of the whole network, and what total voltage corresponds to 5 A through that total? • Given that voltage, what is the voltage across the 15 Ω resistor, and how does that give you the current in just that branch?
• Be sure you are using the parallel resistance formula: 1/R_eq = 1/R1 + 1/R2, not adding them directly • Confirm that the same voltage appears across components that are in parallel • After finding the current in the 15 Ω resistor, check that the sum of currents in parallel branches equals the current entering that parallel section
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