Capacitors Flashcards
What is a capacitor?
Capacitors are electrical components that can store electrical charge.
What is capacitance?
Capacitance is the amount of charge a capacitor can store per unit potential difference across it.
What is the circuit symbol for a capacitor?
The circuit symbol is two parallel lines.
What happens when a capacitor is connected to a d.c. power source?
Charge builds up on its plates, one becoming negatively charged and the other positively charged.
What is the role of the dielectric in a capacitor?
The dielectric is an electrically insulating material that separates the two conducting plates.
How is capacitance measured?
Capacitance is measured in farads (F).
Convert 1 farad to coulombs per volt.
1 farad (F) is equal to 1 coulomb per volt (C/V).
What are the common units for capacitance?
Microfarads (μF), nanofarads (nF), and picofarads (pF).
Fill in the blank: The formula for capacitance is C = _______.
Q/V
What occurs when a capacitor is fully charged?
Current stops flowing in the circuit.
Describe what happens to the current as a capacitor charges.
Initially high, it decreases as the potential difference across the capacitor increases.
What energy is stored in a capacitor?
Electric potential energy is stored as charges are forced together.
How is the energy stored in a capacitor calculated?
The energy stored is the area under the graph of potential difference against charge.
What happens when the e.m.f. source is removed from a charged capacitor?
The capacitor begins to discharge, acting as the circuit’s source of e.m.f.
True or False: The same number of electrons flow from the positive plate as build up on the negative plate.
True.
What is the formula for the energy stored in a capacitor derived from the potential difference?
W = 1/2 QV.
What are some applications of capacitors?
- Flash photography
- Back-up power supplies
- Smoothing out p.d.
Fill in the blank: Capacitors can discharge _______ than batteries.
quicker
What does the area of a triangle represent in the context of capacitors?
It represents the energy stored by the capacitor.
What is the effect of electrostatic repulsion on a charging capacitor?
It makes it harder for more electrons to be deposited as charge builds up.
What is the relationship between potential difference and charge in a capacitor?
The potential difference is directly proportional to the charge stored.
In a potential difference-charge graph, what does the area under the graph represent?
The total energy stored by the capacitor.
