Capacitors: Storing Electrical Energy
Temporary electrical storage
What a capacitor is
A capacitor stores separated charge between two conductive plates with an insulating material called a dielectric between them.
Capacitance
Capacitance describes how much charge a capacitor can store for a given voltage. The unit is the farad, written as .
Charging and discharging
When a capacitor is connected to a voltage source, it charges over time. When the source is removed, it can release stored energy.
Typical uses
Capacitors are used for smoothing power supplies, filtering signals, timing circuits, and storing brief bursts of energy.
Important idea
A capacitor resists sudden changes in voltage, which makes it useful for filtering and timing.
What does a capacitor store?
Capacitors store separated charge and energy in an electric field.
Correct answer: Separated electric charge
What is the unit of capacitance?
Capacitance is measured in farads.
Correct answer: farad
Resistor vs capacitor
Resistor
- Limits current
- Dissipates energy as heat
Capacitor
- Stores energy temporarily
- Responds to changes in voltage over time
Thinking about capacitor behavior
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1
Step 1: Ask whether voltage is changing quickly.
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Step 2: Remember that a capacitor opposes sudden voltage changes.
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Step 3: Predict whether it will charge or discharge.
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Step 4: Use it for filtering, timing, or temporary storage.