C = q/v

Definition

The equation c = q/v defines capacitance (c) as the ratio of the electric charge (q) stored on a capacitor to the voltage (v) across it. This relationship is essential in understanding how capacitors function in electrical circuits, as it shows how much charge can be stored per unit of voltage applied. Capacitors play a vital role in many electronic devices, impacting the overall performance of circuits, especially in terms of energy storage and timing applications.

5 Must Know Facts For Your Next Test

1. Capacitance is measured in farads (F), where 1 farad equals 1 coulomb per volt.
2. A capacitor with a higher capacitance can store more charge at the same voltage compared to one with lower capacitance.
3. Capacitors are used in various applications including filtering, timing, and energy storage in power supply systems.
4. The relationship defined by c = q/v is linear, meaning that if you increase the voltage across a capacitor, the amount of charge stored increases proportionally.
5. In AC circuits, capacitors can also influence the phase relationship between voltage and current due to their reactive properties.

Review Questions

• How does changing the voltage across a capacitor affect its capacitance and stored charge?
  • According to the equation c = q/v, when you increase the voltage (v) across a capacitor while keeping capacitance constant, the amount of stored charge (q) will also increase. This demonstrates that capacitance itself remains constant for a given capacitor, but the amount of charge it can hold directly depends on the applied voltage. Thus, adjusting voltage is key for controlling how much charge is stored.
• What are some practical applications of capacitors that illustrate the importance of understanding c = q/v?
  • Understanding c = q/v is critical in applications such as power supplies where capacitors are used to smooth out voltage fluctuations. In timing circuits like oscillators, capacitors determine the time constants based on their capacitance and the resistance in the circuit. Additionally, capacitors in filtering circuits help eliminate unwanted frequencies by charging and discharging according to this fundamental relationship, ensuring devices operate efficiently.
• Evaluate how variations in capacitance affect the transient response in circuits that use capacitors.
  • Variations in capacitance can significantly impact the transient response of circuits involving capacitors. For instance, larger capacitance results in slower charging and discharging rates due to increased stored charge according to c = q/v. This affects how quickly a circuit can respond to changes in voltage or current, influencing overall circuit behavior during transient conditions. Analyzing these effects allows engineers to design circuits with desired response times for specific applications, such as filtering or timing operations.

Related terms

Capacitance: The ability of a system to store an electric charge, measured in farads (F), which indicates how much charge can be stored per volt.

Voltage: The electric potential difference between two points in a circuit, driving the flow of electric current and measured in volts (V).

Charge: The physical property of matter that causes it to experience a force when placed in an electromagnetic field, measured in coulombs (C).