Summary
Summary Capacitance
- Course
- Institution
Key concepts of unit 4 A2 physics
[Show more]
Seller
Follow
careyneale2005
Content preview
capacitance is the charge stored by a capacitor ✓ = potential differenceper volt of potential difference applied across it. (= capacitance A
C. = EOA CNA Caf
unit = farad, F (F = CV-1) Q = charge d
symbolz d
Ecoon=stPañtm "(8"!"85×1%-1? ing
Q = CV C- Q
v. ♀ Tip: to increase capacitance
of capacitor add a dielectric
Charging of a capacitor
+ The greater the potential Charging Equations: Discharging Equations:
V difference across capacitor Vo, Qo, Io = Initial max value i. V0 = E
the greater the charge that Q = Qo (Y-éᵗ/RC) Q = éᵗ're
can be stored. Charging Graphs: discharging graphs:
✓ = ECT - e- "RC) V-Ee-"RC
c
Q
QαV
If a resistor is added R
then the ÷ ¾
⟂-Io (t-e- "RC) I - I, e-t/RC
charging process takes longer as resistors
resist flow of charge. time time TIME CONSTANT: T = RC
R
E- emf: supply voltage the time constant for an RC circuit is the time it
Vo: E
t takes the charge across the capacitor to fall to
V
o
v i
E - Vc + Vr if V=IR : e 37% of it's original value.
E = Vct IR
t time time discharged by 371. so 631. charge left.
E
ENERGY STORED BY CAPACITOR if By substituting t-RC into discharging equations:
l
a charged capacitor is a store of electrical energy. É Q = ◦ e- "RC same fo
work done: voltage-work done per coulomb = Qoe-RC/RC - RC = -1 V. Q,
W= V RC
time time
Average Voltage: Energy stored = =Q e-t e- 1 = 0.37 = 371. discharged
= V10 = ½ V area under a Q-V graph CAPACITORS IN CIRCUITS:
gradient = %
Total Energy stored :
U =½QV or U=½CV² or = ½
♀
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller careyneale2005. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $3.89. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
73216 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now