DC Circuits

RESISTORS IN PARALLEL

Question

In the following schematic diagram, find the total current, I.

Figure 1 Example Problem: Resistors in Parallel

Hints

1. You will need Ohm's Law.
2. How are resistors related when connected in parallel?
3. What is the potential drop across each resistor?
4. How does current behave in parallel branches?
Solution
We know the total potential of this circuit,
= 12.0 V
So, between points A and B, the potential must drop 12.0V. Also, the potential drop across branches of a circuit are equal. That is,
We can use Ohm's Law
V = IR
or
I = V/R
to find the current across each resistor.

Recall that the currents through branches of a parallel circuit add to give the total current. That is, the total current 'splits up' so that part of the total current travels down each branch. Because of conservation of charge, the sum of the currents in each branch must equal the amount going into the branch. (This is Kirchhoff's Current Law.)
So, adding up the three currents, we get:
So, the total current is I = 12.0A.

Explanation of Resistors in Parallel
Continue to:Resistors in Combination
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