External Exam Revision
Learn Coach Level 3 Physics Link
Wednesday, 14 October 2020
Monday, 24 August 2020
Term 3 Week 6 2020
Homework
Right Hand Screw Rule
Right Hand Slap Rule
Magnetic Flux
Lenz's Law
Faraday's Law & Lenz's Law
Inductance
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
Monday, 3 August 2020
Term 3 Week 3 2020
Homework
Ex 6A, p.251-254 Level 2 D.C. Circuit Revision Ex 6B, p.261-261 Internal Resistance of a Battery Ex 6C, p.267-272 Kirchhoff's Laws Ex 6D, p.277-280 Capacitors Ep = ½ QV Ex 6E, p.283-284 Capacitors C = 𝜺r𝜺oA/d Ex 6F, p.289-292 Capacitor Networks (Series & Parallel) Ex 6G, p.298-300 Capacitor Charge & Discharge
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 CapacitanceC = 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
Thursday, 30 July 2020
Term 3 Week 2 2020
Homework
Ex 6A, p.251-254 Level 2 D.C. Circuit Revision
Ex 6B, p.261-261 Internal Resistance of a Battery
Ex 6C, p.267-272 Kirchhoff's Laws
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
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”
“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
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