Week 2 Term 3 2025 D.C. Electric Circuits

Homework:

Electric Fields

• Act 17A, p.192-194, Electric Fields
• Ex 6A, p.188-196, Static Electric Fields

DC Electric Circuits

• Act 18A, p.201 Intro DC Electricity
• Act 18B, p.207 Simpler Equivalent Circuits
• Act 18C, p.209 Potential Dividers
• Act 18D, p.211-213 Using Ohm's Law
• Ex 6B, p.200-201 Voltage and Current
• Ex 6C, p.205-214 D.C. Circuits

Current

Current is the rate of flow of Charge

I = Δq/Δt

Current

Voltage

Voltage (Potential Difference) is the change in energy (work done) to each coulomb of charge between two points on a circuit, or two points across an electric field

Circuit Symbols

Ohm's Law

Ohm's Law PhET application

D.C. Circuit Construction Kit PhET Application

D.C. Circuit Lab PhET Application

Ohm's Law

Series & Parallel Circuits

Series & Parallel Circuits

Electric Power

P = IV

P = I2R  ← using Ohm’s Law V=IR substitution

P = V2/R←using Ohm’s Law I=V/R substitution

Week 1 Term 3 2025 Uniform Electric Fields

   Homework:

Electric Fields

• Act 17A, p.192-194, Electric Fields
• Ex 6A, p.188-196, Static Electric Fields

PhET - Charge & Electric Fields - App

Basics of Electric Charge

Definition of an Electric Field:

“Any region of space where a charge feels a force.”

A positive charge will feel a force with the electric field direction

A negative charge will feel a force against the electric field direction

Fe = Eq

Electric Field

Electric Potential (Voltage)

What is Voltage?

Uniform Electric Field

E = V/d

Uniform Electric Fields

Uniform Electric Fields, Derivation of E=V/d

Charges in Uniform Electric Fields: Forces & Acceleration

Uniform Electric Field

E = V/d

E: Electric Field (Vm-1 or NC-1 depending on the context

used)

Electric Force

Fe = Eq

Fe: Electrical Force (N)

q or Q: Charge (C)

Electrical Potential Energy

As the charge falls through the Electric Field, the electrical potential energy transforms into kinetic energy.

Ek = Ep

½ mv2 = Vq

Electron Gun

(Cathode Ray Tube)

A Tube Screen TV is an Electron Gun

Cathode Ray Tube and how it works

Electron Gun

Cathode Ray Tube (CRT)

Discovery of the Electron: Cathode Ray Tube Experiment

Cathode Rays Leads to Thomson's Model of the Atom

Parker Solar Probe - Use of CRT

Millikan's Oil Drop Experiment

Charge of an Electron - Millikan's Oil Drop Experiment