Module 6 - 6.1.2 Energy Flashcards

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1
Q

The energy stored by a capacitor must equal

A

the work done to separate the charges on the two plates

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2
Q

Charge is proportional to

A

Pd, where constant of proportionality = capacitance

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3
Q

Charge - Pd Graph (2)

A
  • gradient = capacitance
  • area underneath = energy stored in capacitor
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4
Q

Capacitors discharge

A

slowly due to charge leakage, so the stored energy decreases

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5
Q

Uses of Capacitors

A

Flash devices for cameras
- charge is stored in capacitor and released quickly
- resulting high current excites a gas resulting in the energy being converted to a bright flash of light

Back up energy supplies
- large capacitors are used in back up power supplies in data centres to provide emergency current for a very short time
- long enough to shut down equipment and save data if mains power fails

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