Week 4 Term 3 2025 Inductors

  Basic Circuit Revision

• Act 13A, p.205-206 Level 2 D.C. Circuit Revision

Internal Resistance of a Battery

• Act 13B, p.210-211 Internal Resistance of a Battery

• Ex 6B, P.261-262 Internal Resistance of a Battery

Resistor Networks (Resistors in Series and Parallel)

• Ex 6A, p.251-253 Resistor Networks

Kirchhoff’s Laws

• Act 13C, p.214-216 Kirchhoff's Laws

• Ex 6C, p.267-272 Kirchhoff's Laws

Capacitors

• Act 14A, p.240 Capacitance & Capacitors

• Act 14B, p.244-245 Capacitor Networks & Energy

• Act 14C, p.249-251 Charging & Discharging Capacitors

• Ex 6D, p.277-280 Capacitor Energy

• Ex 6E, p.283-284 Capacitors

• Ex 6F, p.289-292 Capacitor Networks

• Ex 6G, p.298-300 Charging & Discharging Capacitors

Inductors

• Act 15A, p.259-260 Induced Voltage & Current

• Act 15B, p.263-264 Transformers

• Act 15C, p.268-269 Inductance

• Act 15D, p.272-273 Voltage and Current Graphs for the Inductor

• Ex 6H, p.303-305 Inductance in DC Circuits

• Ex 6I, 308-310 Inductance: Self; Mutual; Time Constant; Energy Stored

• Ex 6J, p.311-312 Transformers

Right Hand Screw Rule

Right Hand Slap Rule

Magnetic Flux

Faraday's Law - PhET Application

Lenz's Law

Faraday's Law & Lenz's Law

Inductance

Inductors Explained - The basics how inductors work working principle

Inductor PhET Demonstration

Transformers

The ratio of the secondary to primary voltage is equal to the ratio of the secondary to primary turns

Vs/Vp = Ns/Np

In an Ideal Transformer 

Secondary Power = Primary Power

In reality, energy is lost through heat from eddy currents generated in the soft iron core from the changing flux.

NB: As Voltage is often referred to as e.m.f. the Symbol "e" or "E" is often used in engineering to refer to e.m.f.

This is the case in the video below.

After explaining how basic Transformers work, this video goes on to explain 3-Phase Transformers.

NZ Street Step-Down Transformer

Internal Diagram of a Transformer

How Do Substations Work?

Fuse MCB, How it Works

Week 3 Term 3 2025 Capacitors

 Basic Circuit Revision

• Act 13A, p.205-206 Level 2 D.C. Circuit Revision

Internal Resistance of a Battery

• Act 13B, p.210-211 Internal Resistance of a Battery

• Ex 6B, P.261-262 Internal Resistance of a Battery

Resistor Networks (Resistors in Series and Parallel)

• Ex 6A, p.251-253 Resistor Networks

Kirchhoff’s Laws

• Act 13C, p.214-216 Kirchhoff's Laws

• Ex 6C, p.267-272 Kirchhoff's Laws

Capacitors

• Act 14A, p.240 Capacitance & Capacitors

• Act 14B, p.244-245 Capacitor Networks & Energy

• Act 14C, p.249-251 Charging & Discharging Capacitors

• Ex 6D, p.277-280 Capacitor Energy

• Ex 6E, p.283-284 Capacitors

• Ex 6F, p.289-292 Capacitor Networks

• Ex 6G, p.298-300 Charging & Discharging Capacitors

Capacitor

C = Q/V

Capacitors

Basic Definition

Physical Parameters

Energy Stored

Ep = ½ QV

Capacitors & Capacitance

Capacitors Explained

Dielectric

An insulating material placed in between the capacitor plates to increase the Capacitance

C = 𝜺r𝜺oA/d

Dielectrics in Capacitors

PhET Capacitor Lab Basics - App

Capacitor Circuits

Capacitors in Series

Calculating Voltage Charge and Total Capacitance

Capacitors in Parallel

Calculating Voltage Charge and Total Capacitance

Capacitors in Parallel vs Capacitors in Series

Capacitors in Combination

Series & Parallel Capacitors

Capacitors in Combination

Patrallel & Series Capacitors

Capacitors in Series

Calculating Voltage Drop

Capacitors in Series

Calculating the Charge Stored

Capacitors in Series

Calculating the Equivalent Capacitance

Capacitors in Parallel

Calculating Voltage Drop

Capacitors in Parallel

Calculating the Charge Stored

Capacitors in Parallel

Calculating the Equivalent Capacitance

Capacitor Charge & Discharge

RC Circuits 1: Charging and Discharging a Capacitor

Week 2 Term 3 2025 Internal Resistance of a Battery & Kirchhoff's Laws

  Homework

Act 13A, p.205-206 Level 2 D.C. Circuit Revision

Act 13B, p.210-211 Internal Resistance of a Battery

Ex 6A, p.251-253 Resistor Networks

Ex 6B, P.261-262 Internal Resistance of a Battery

Electrical Charge

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

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

V = ΔE/Q

Ohm's Law & Resistance

Power

Circuit Symbols

Ohm's Law

Ohm's Law - PhET App

D.C. Circuit Construction Kit - PhET App

Ohm's Law

Internal Resistance of a Battery

Batteries can be thought of as having an ideal voltage supply E.M.F. (Electromotive Force) in series with an internal resistance

V = 𝛆 - Ir

How to find the internal resistance of a battery

Kichhoff's Laws

Kirchhoff’s Current Law
“At any junction in a circuit, the total current entering the junction equals the total current leaving the junction”
Kirchhoff’s Voltage Law
“Around any closed path of a circuit, the total of all the potential differences, V, is zero”

Kirchhoff's Rules for Circuit Analysis - Explanation

Kirchhoff's Rules for Circuit Analysis - Example 1

Kirchhoff's Rules for Circuit Analysis - Example 2

Kirchhoff's Rules for Circuit Analysis - Example 3