Capacitors

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SAT Subject Test in Physics › Capacitors

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A capacitor with capacitance is constructed by putting a thin piece of cardboard between two copper plates, then each plate is connected to a battery. If the copper plates are cut in half then what is the effect on the capacitance of the circuit?

$\frac{1}{2}C$

$\frac{1}{C}$

$C^{2}$

Explanation

Capacitance of a circuit is defined by the equation:

$C=\varepsilon\frac{A}{d}$

Where is the capacitance, $\varepsilon$ is a constant of nature, is the area of the capacitor, and is the distance between the two plates

Since the metal plates are cut in half, the area is halved. We can substitute $\frac{1}{2}A$ in for

The result is that the capacitance is half the original quantity.

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