Week 8 Term 3 Two Point Source Interference

  Homework:

Basic Properties of Waves

• Act 5A, p,53, Pulses and Waves
• Ex 3D, p.66--67, Wave Properties

Superposition & Diffraction

• Ex 3F, p.3F, p.73-75 Superposition
• Act 5B, p. 58, Reflection, Refraction and Diffraction of Waves
• Act 5C, p.63-64, Diffraction and Superposition
• Ex 3E, p.69-70, Diffration
• Ex 3H, p.81-83 Waves on a String
• Ex 3I, p.85-87 Wave Refraction on a String

Young’s Double Slit Experiment

• Ex 3B, p. 47-52, Refraction
• Ex 3G, p.76-78 Two Point Source Interference

Reflection, Refraction and Diffraction

• Act 5B, p. 58, Reflection, Refraction and Diffraction of Waves

Diffraction

Diffraction of Water Waves in a Ripple Tank

Two Point Source Interference

Two Point Source Interference

Double Slit Experiment

PhET Sound Wave Interference - link

PhET Wave Interference - link HTML

Snell's Law & Critical Angle

The Critical Angle occurs when a wave is attempting to pass from a medium with a slower speed to that of a higher speed 

low v → higher v

low 𝜆 → higher 𝜆

high n → lower n

The Critical angle is the incident angle where the refracted angle equals 90 degrees

Refraction Bending Light PhET Application

Snell's Law

• Any incident above the Critical angle will prevent any refraction occuring and Total Internal Reflection will occur
• The Critical angle is can be found by sin(𝜭c) = n2/n1

FibreOptic Cables: How they work?

Total Internal Reflection T.I.R.

What Happens to Lazers Underwater?

Week 7 Term 3 2025 Waves & Basic Wave Properties

 Homework:

• Act 5A, p,53, Pulses and Waves
• Ex 3D, p.66--67, Wave Properties
• Ex 3F, p.3F, p.73-75 Superposition
• Act 5B, p. 58, Reflection, Refraction and Diffraction of Waves
• Act 5C, p.63-64, Diffraction and Superposition

Basic Properties of Waves

waves transfer energy through a medium without transferring the medium itself

• Cycle - a basic repeating unit in a wave
• Amplitude A (m) - the distance from the middle point to the top of a crest, or bottom of a trough
• Wavelength 𝜆 (m) - the distance/length of one cycle
• Period T (s = s per cycle) - the time it takes for one cycle to pass a point
• Frequency f (Hz = cycles per second) - the number of cycles that pass in one second

T = 1/f & f = 1/T

• Wave Speed v (ms-1) the speed of a wave

v = 𝜆/T & v = f𝜆

Wave Properties

Frequency & Period

Wave Phase

Pendulum Waves

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

• Superposition of Waves: two waves traveling through each other will not change each other motion in any way, but they will add to one another when they overlap
• Constructive Interference - Reinforcement - In Phase
• Destructive Interference - Cancellation - Out of Phase

PhET Waves on a String App - link

Reflection on A String

Hard Boundary

Wave reflects on opposite side (opposite phase)

Same Amplitude, A

Same Wavelength, 𝛌

Same Wave Speed, v

Reflection on A String

Soft Boundary

Wave reflects on same side (same phase)

Same Amplitude, A

Same Wavelength, 𝛌

Same Wave Speed, v

Refraction on A String

Fast to Slow Boundary

Relation of waves to Incident Wave

Reflected Wave - same speed - same wavelength 𝛌 - opposite phase

Refracted Wave - slower speed - smaller wavelength 𝛌 - same phase

Refraction on A String

Slow to Fast Boundary

Relation of waves to Incident Wave

Reflected Wave - same speed - same wavelength 𝛌 - same phase

Refracted Wave - faster speed - larger wavelength 𝛌 - same phase

Diffraction

• The Bending of Waves Around Corners
• Larger Wavelength, 𝛌 - greater the angle of diffraction
• Shorter Wavelength, 𝛌 - smaller the angle of diffraction
• Also the smaller the gap the greater the angle of diffraction

Diffraction

Diffraction of Water Waves in a Ripple Tank

Cymatics

Cymatics

Cymatics: Hose Pipe Water Experiment

Singing plates - Standing Waves on Chladni plates

Cymatics: Ruben's Tube Vs. Tesla Coil

Sound + Fire = Rubens' Tube

A better description of resonance

Week 5 Term 3 2025 Magnetism

 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

Magnetic Fields

• Act 19A, p.219-220 Magnets
• Act 19B, p.223-225 F = BIL Lorentz
• Act 19C, p.228 F = Bqv Lorentz
• Ex 6D, p.218-220 F = BIL Lorentz
• Ex 6E, p.222-224 F = Bqv Lorentz
• Ex 6F, p.227-228 V = BvL Induced EMF
• Act 20A, p.231-232 Induction
• Act 20B, p.235-237 V = BvL Induction

Magnetic Fields






Magnets 

Why Do Magnets Attract, at a Fundamental Level? Why? Why? Why?

Electromagnet

Earth & Compasses - Magnetism





Electromagnet Used for Scrap Metal Crane



Levitating with Electromagnets


Exploding Cans with Electromagnets


Magnetic Fields




Right Hand Screw Rule





Right Hand Slap Rule



Right Hand Slap (Palm) Rule


Lorentz Force (F = Bqv)


Lorentz Force





Lorentz Force



Lorentz Force (F = BIL)


                                       





V = BvL

Note:
• emf is an old term for voltage and stands for electromotive force
• E is also used by enginers for Voltage (not energy)


D.C. Motor




D.C. Motor How it Works





Brushless D.C. Motor How it Works







Faraday Cage




Tesla Coil & Faraday Cage