Term 2 Week 9 2019

Homework

• Ex 3I, p.85-87 Wave Refraction on a String
• Ex 3B, p. 47-52, Refraction

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

• 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?

Term 2 Week 8 2019

Homework

• Ex 5A, p. 151-155, Models of the Atom
• Ex 5B, p. 160-171, Radioactivity
• Ex 5C, p. 175-182, Nuclear Reactions

Phy 2.5 AS 91172

Atomic & Nuclear Physics Assessment this Thursday 20th June Period 4

Term 2 Week 6 2019

Homework

• Ex 5A, p. 151-155, Models of the Atom
• Ex 5B, p. 160-171, Radioactivity
• Ex 5C, p. 175-182, Nuclear Reactions

Nuclear Reactions:

• Conservation of Atomic Number
• Conservation of Nucleon Number
• Conservation of Mass-Energy E = Δmc2

E = Δmc2

Nuclear Fusion in the Sun

Binding Energy comes from the change in mass from individual nucleons to being combined into a nucleus. This is energy lost by the nucleons joined together in a nucleus and must be returned in order to separate the nucleons

E = Δmc2

Mass Energy Equivalence

Nuclear Reactions

Fission Fusion and Radioactive Decay

Fission & Fusion

Term 2 Week 5 2019

Homework

• Ex 3D, p.66--67, Wave Properties
• Ex 3E, p.69-70, Diffration
• Ex 3F, p.3F, p.73-75 Superposition
• Ex 3G, p.76-78 Two Point Source Interference
• Ex 3H, p.81-83 Waves on a String
• Ex 3I, p.85-87 Wave Refraction on a String
• Ex 5A, p. 151-155, Models of the Atom
• Ex 5B, p. 160-171, Radioactivity
• Ex 5C, p. 175-182, Nuclear Reactions

Models of the Atom

History of the Atom

Models of the Atom Timeline

Discovery of the Electron: Cathode Ray Tube Experiment

Discovery of the Nucleus: Rutherford's Gold Foil Experiment

Charge of an Electron: Millikan's Oil Drop Experiment

Atomic Structure: Discovery of the Neutron

Parts of the Atom

Isotopes

Isotopes are versions of an atom or an element that have the same number of protons, but different numbers of neutrons

What are Isotopes?

Radioactive Decay

Alpha, Beta & Gamma Radiation

• Alpha particles are emitted by a larger nucleus that has too many Protons
• Beta particles are emitted by a nucleus that has too many Neutrons
• Gamma photons are emitted by a nucleus that has too much Energy (is in an exited state)

• PhET Alpha Decay app can be found here
• PhET Beta Decay app can be found here

Alpha Decay

Beta Decay

Radiation

Types of Radiation

Is radiation dangerous?

The Most Radioactive Places on Earth

Millisieverts and Radiation - Sixty Symbols

Term 2 Week 4 2019

Homework

• Ex 3D, p.66--67, Wave Properties
• Ex 3E, p.69-70, Diffration
• Ex 3F, p.3F, p.73-75 Superposition
• Ex 3G, p.76-78 Two Point Source Interference
• Ex 3H, p.81-83 Waves on a String
• Ex 3I, p.85-87 Wave Refraction on a String

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

Two Point Source Interference

Two Point Source Interference

Double Slit Experiment

PhET Sound Wave Interference - link

PhET Wave Interference - link

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

Term 2 Week 3 2019

Homework

• Ex 3D, p.66--67, Wave Properties
• Ex 3E, p.69-70, Diffration
• Ex 3F, p.3F, p.73-75 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