Parallel Circuit Physics Example 1

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Example 1

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Two resistors (6 Ω6 \text{ } \Omega and 12 Ω12 \text{ } \Omega) are connected in parallel to a 12 V12 \text{ V} battery. What is the total resistance and the current through each resistor?

Solution

  1. 1
    Total resistance: 1RT=16+112=212+112=312    RT=4 Ω\frac{1}{R_T} = \frac{1}{6} + \frac{1}{12} = \frac{2}{12} + \frac{1}{12} = \frac{3}{12} \implies R_T = 4 \text{ } \Omega
  2. 2
    Current through 6 Ω6 \text{ } \Omega: I1=VR1=126=2 AI_1 = \frac{V}{R_1} = \frac{12}{6} = 2 \text{ A}.
  3. 3
    Current through 12 Ω12 \text{ } \Omega: I2=VR2=1212=1 AI_2 = \frac{V}{R_2} = \frac{12}{12} = 1 \text{ A}.
  4. 4
    Total current: IT=2+1=3 AI_T = 2 + 1 = 3 \text{ A} (consistent with V/RT=12/4=3 AV/R_T = 12/4 = 3 \text{ A}).

Answer

RT=4 Ω;I1=2 A,I2=1 AR_T = 4 \text{ } \Omega; \quad I_1 = 2 \text{ A}, I_2 = 1 \text{ A}
In parallel circuits, voltage is the same across all branches. The total resistance is less than the smallest individual resistance, and more current flows through the smaller resistor.

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A parallel circuit connects components in separate branches between two common nodes, so each component gets the full source voltage.

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