This aesthetic, in-depth, neatly typed document summarises Section E of the IEB Grade 12 Physics syllabus: Electric circuits. This document includes the full Section E syllabus, all definitions, additional class notes, own research notes and all relevant diagrams.
Electric Circuits:
Voltage: Work done per unit positive charge OR Energy transferred per unit positive charge
W • V : Voltage (Volts, V)
V = • W : Energy (Joule, J)
Q
• Q : Charge (Coulomb, C)
• What happens to electron in resistor: Electron gives o heat energy & loses kinetic energy
• Energy conversion in resistor: Ekinetic ! Ethermal
• Voltage across BATTERY = energy given TO charges by battery
• Voltage across RESISTOR = energy taken FROM charges by resistor
EMF:Total energy supplied per coulomb of charge by cell.
• Taken with a voltmeter across battery when battery is NOT delivering current to circuit.
• Vext: Vload measured across battery when current is owing
• emf = Vext + Vint • Vint: Inside battery
r = internal resistance of battery
Electric current: Rate of ow of charge
q • I : Current (Ampere, A)
I= • q : Charge (Coulomb, C)
¢t • t : Time (Seconds, s)
Resistance: A material's opposition to the ow of electric current
• R (Ohms, « )
• Resistance depends on:
- Type of material
- Length of conductor (Increased length = decreased resistance)
- Diameter of conductor (Increased diameter = decreased resistance)
- Temperature
fl
, Ohm's Law: Current through conductor is directly proportional to potential di erence across the
conductor at a constant temperature
V
R=
I
Rheostat: Variable resistor
or
Ohmic conductors: Have constant resistance no matter what the voltage across or current through it
is.
Non-ohmic conductors: Have varying resistance that depends on current through it
Series circuit:
• Resistance in series: Rseries = R1 + R2:::
• Why Vext decreases when resistor in series is removed:
Rext decreases (De nition of R)
I increases (De nition of R)
Vint increases (Vint = I.r) (r is constant)
emf = Vext + Vint
Vext = emf - Vint (emf constant)
,Therefore Vext decreases
Parallel circuit:
1 1 1
• Resistance in parallel: = + :::
Rp R1 R2
ff
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 Lindyprinsloo. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $4.40. You're not tied to anything after your purchase.
