Question

Difficulty: EasyCapacitors and Capacitance

Two capacitors with capacitances of 3.0 μF3.0\text{ }\mu\text{F} and 6.0 μF6.0\text{ }\mu\text{F} are connected in parallel across a direct-current source. What is the equivalent capacitance of this combination?

  1. 9.0 μF9.0\text{ }\mu\text{F}Answer
  2. B
    2.0 μF2.0\text{ }\mu\text{F}
  3. C
    4.5 μF4.5\text{ }\mu\text{F}
  4. D
    18.0 μF18.0\text{ }\mu\text{F}

Answer

The equivalent capacitance of the parallel combination is 9.0 μF9.0\text{ }\mu\text{F}.
When capacitors are connected in parallel, each capacitor experiences the full potential difference of the voltage source, and the total charge stored is the sum of individual charges (Qtotal=Q1+Q2Q_{total} = Q_1 + Q_2). Thus, the equivalent capacitance is the direct sum of the individual capacitances: Ceq=3.0 μF+6.0 μF=9.0 μFC_{eq} = 3.0\text{ }\mu\text{F} + 6.0\text{ }\mu\text{F} = 9.0\text{ }\mu\text{F}.

Step-by-Step Solution

1
Identify the combination rule for parallel capacitors.
The total capacitance is given by Ceq=C1+C2C_{eq} = C_1 + C_2.
Capacitors in parallel share the same potential difference, so total charge stored is the sum of individual charges.
2
Substitute the given values into the parallel capacitance formula.
Ceq=3.0 μF+6.0 μF=9.0 μFC_{eq} = 3.0\text{ }\mu\text{F} + 6.0\text{ }\mu\text{F} = 9.0\text{ }\mu\text{F}.
Direct addition yields the total equivalent capacitance.

Key Concept

Parallel Combination of Capacitors
Estimated Time:45s
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