Capacitors

Definition

Capacitors are passive electronic components that store electrical energy in an electric field. They are fundamental building blocks in electronic circuits, used for various purposes such as filtering, timing, and energy storage.

5 Must Know Facts For Your Next Test

1. The capacitance of a capacitor is determined by the area of its plates, the distance between the plates, and the dielectric material used.
2. Capacitors in series have a total capacitance that is less than the capacitance of any individual capacitor, while capacitors in parallel have a total capacitance that is the sum of the individual capacitances.
3. The energy stored in a capacitor is proportional to the square of the voltage across the capacitor and the capacitance.
4. Capacitors are used in electronic circuits for filtering, bypassing, timing, and energy storage applications.
5. The voltage rating of a capacitor indicates the maximum voltage it can safely withstand without breaking down the dielectric material.

Review Questions

• Explain how the arrangement of capacitors in a circuit (series or parallel) affects the total capacitance.
  • When capacitors are connected in series, the total capacitance is less than the capacitance of any individual capacitor. This is because the reciprocal of the total capacitance is the sum of the reciprocals of the individual capacitances. Conversely, when capacitors are connected in parallel, the total capacitance is the sum of the individual capacitances. This is because the total charge stored is the sum of the charges stored in each capacitor, and the voltage across each capacitor is the same.
• Describe how the energy stored in a capacitor is related to its capacitance and the voltage across it.
  • The energy stored in a capacitor is proportional to the square of the voltage across the capacitor and the capacitance of the capacitor. Specifically, the energy stored is given by the formula $E = \frac{1}{2}CV^2$, where $E$ is the energy stored, $C$ is the capacitance, and $V$ is the voltage across the capacitor. This relationship demonstrates that increasing the voltage or the capacitance of a capacitor will result in a greater amount of energy stored in the electric field between the plates.
• Analyze the factors that determine the capacitance of a capacitor and explain how these factors can be manipulated to achieve desired capacitance values.
  • The capacitance of a capacitor is determined by three main factors: the area of the plates, the distance between the plates, and the dielectric material used. Increasing the plate area or decreasing the distance between the plates will both result in an increase in the capacitance. Additionally, using a dielectric material with a higher permittivity will also increase the capacitance. By carefully selecting the size of the plates, the spacing between them, and the dielectric material, engineers can design capacitors with a wide range of capacitance values to meet the specific needs of electronic circuits.

Related terms

Capacitance: The measure of a capacitor's ability to store an electric charge, typically expressed in Farads (F).

Electric Field: The force exerted by electric charges on other charges in the surrounding space.

Dielectric: An insulating material placed between the plates of a capacitor, which allows for the storage of electric charge.