Term 4 Week 3 2016

A.C. Circuits & Resonance

Mechanics 2015 Question 3 on Cats & Gravity (Conservation of Angular Momnetum L=Iω) 

Examination Paper 2015  AS 91524

Assessment Scedule 2015 AS 91524

Mechanics 2014 Question 3 Translational Motion (2D Momentum) by Cameron Urban
can be found at the bottom of the mechanics page

Waves Exam Revision

NCEA Physics L3 Waves: Introduction

NCEA Physics L3 Waves: Standing waves

NCEA Physics L3 Waves: Standing wave harmonics

NCEA Physics L3 Waves: Standing wave questions

NCEA Physics L3 Waves: Doppler effect

NCEA Physics L3 Waves: Doppler calculations

NCEA Physics L3 Waves: Doppler questions

NCEA Physics L3 Waves: Mulit slit interference

NCEA Physics L3 Waves: Mulit slit calculations


NCEA Physics L3 Waves: Mulit slit questions

Term 4 Week 2 2016

Review of Electricity Mock Exam

NZIP 2016 Exam Phy 3.6 AS 91526

RCL Phase Relationships

MIT Mathlet on RCL Phase Relationships - Interactive

UNSW Animations for RCL Phase Relationships

Impedance of a Capacitor Resistor Circuit

Z = √(XC2 + R2)

θ = tan-1(-XC/R) = tan-1(-VC/VR)

The Capacitor Reactance is 90° behind the Resistance

The Capacitor Voltage is 90° behind the Resistor Voltage

Impedance of a Inductor Resistor Circuit

Z = √(XL2 + R2)

θ = tan-1(XL/R) = tan-1(VL/VR)

The Inductor Reactance is 90° ahead of the Resistance

The Inductor Voltage is 90° ahead of the Resistor Voltage

Term 4 Week 1 2016

Review of Waves Mock Exam

NZIP 2016 Exam Phy 3.3 AS 91523

Term 3 Week 9 2016

Review of Mechanics Mock Exam

NZIP 2016 Exam Phy 3.4 AS 91524

Term 3 Week 8 2016

Homework

• Questions 1-7, p.128-132 Simple Induction
• Question 9, p. 136 Transformers

Inductance

Inductor PhET Demonstration

Term 3 Week 7 2016

Homework

• Ex 7, p.120 -124, Capacitors
• Questions 1-7, p.128-132 Simple Induction
• Question 9, p. 136 Transformers

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

Faraday Cage

Tesla Coil & Faraday Cage

Tesla Coil & Faraday Cage

Exploding Cans with Electromagnets

Levitating with Electromagnets

Term 3 Week 6 2016

Term 3 Week 6 2016

Homework

• Ex 7, p.120 -124, Capacitors
• Questions 1-7, p.128-132 Simple Induction

Right Hand Screw Rule

Right Hand Slap Rule

Magnetic Flux

Lenz's Law

Faraday;'s Law & Lenz's Law

Term 3 Week 5 2016

Term 3 Week 5 2016

Homework

• Ex 6, p. 108-110, D.C. Circuits
• Q 3, 4, 5, p. 116 Capacitance and Stored Energy
• Ex 7, p.120 -124, Capacitors

Capacitance

Dielectric

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

With a Dielectric the Capacitance formula becomes

C = 𝜺r𝜺oA/d

PhET Application on Capacitors & Dielectrics

Networks of Capacitors

Capacitor Networks & Energy

Energy Stored in a Capacitor

Charge & Discharge of Capacitor

Term 3 Week 4 2106

Term 3 Week 4 2016

Homework 

• Ex 6, p. 108-110 D.C. Circuits

Electrical Charge

Electrical Current

Current is the rate of flow of charge

I = ΔQ/Δt

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

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”

Term 3 Week 2 2016

Term 3 Week 2 2016
Homework:

• Ex 4, p.78-81, Standing Waves & Music
• Ex 5, p.96-99, Superposition (Two-Point Source & Multi-Point Source Interference) & The Doppler Effect

Two Point Source Interference

n𝜆 = dsin(𝛳)

Wave-Particle Duality Applied to the Double Slit Experiment

Diffraction Grating of White Light 

(Multi-Point Source Interference)

Green vs White Light Diffraction

Thin Film Interference

Making Colour with Holes

Visible Spectrum

Why Maths is Important to Understanding the Universe

Term 3 Week 1 2016

Term 3 Week 1 2016

Homework

• Ex 4, p. 78-81, Standing Waves & Music

Longitudinal Waves

Particle displacement in the medium is parallel to the direction of wave propagation e.g. sound waves, primary earthquake waves

Transverse Waves

Particle displacement in the medium is perpendicular to the direction of wave propagation e.g. light and other electromagnetic waves, secondary earthquake waves

Wave Speed

v = f𝜆

Superposition of Waves

Waves travel through each other and the total amplitude at any moment is equal to the sum of amplitudes of the individual waves.

Standing Waves

In musical instruments - when a reflected wave travels back through itself causing fixed points of Nodes (Deconstructive Interference) and Antinodes (Constructive Interference) due to the fractional relationship between the wavelength (𝜆) of the wave and the length (L) of the resonating chamber

Standing Waves on a String

1st Harmonic	2nd Harmonic	3rd Harmonic	4th Harmonic
𝜆 = 2L	𝜆 = L	𝜆 = ⅔ L	𝜆 = ½ L
f = f1st	f = 2f1st	f = 3f1st	f = 4f1st

Standing Waves in a Pipe

Standing Waves on a 2D Plate

Cymatics

Doppler Effect

the observed increase or decrease in frequency of waves (e.g. sound, light) due to the relative movement of the source of waves to the observer

f’ = f vw/(vw ± vs)