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Writer's picturekeshprad

Barron's 2nd Edition PT1 Q48


48) This question asks us to find the current through the 1 Ohm resistor. For simple DC circuits, the total current is the same as the current through each resistor. For parallel circuits, the total current is a sum of the current through parallel resistors. You can refer to the cheat sheet below for simple circuits.

Where V is voltage, I is current, R is resistance, and C is capacitance

Since the 1 Ohm resistor, R[3], is connected in series to the circuit, the total current of the circuit will be equal to the current through R[3]. In order to find the total current, we will need to find the equivalent resistance.


Referring back to the cheat sheet I provided above, we can use the resistance in parallel and resistance in series formulas to find the equivalent resistance of this circuit. Let's start with R[1] and R[2], which are connected in parallel.

Where R is resistance

Next, we will redraw the circuit and use the series formula to find the equivalent resistance.

Where R is resistance, and V is voltage

Our equivalent resistance is 3 Ohms and the battery provides 6 Volts. Using Ohm's law, we can solve for the total current flowing through the circuit.

Where V is voltage, I is current, and R is resistance

Answer: C

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