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

Term 2 Week 2 2019

Homework:

• Ex 4J, p. 143-147 Energy, Work, Power
• Ex 4I, p.137-141, Springs
• Ex 4G, p.125-130, Torque - Static Moments

Torque

𝝉 = F L⦜

𝝉: Torque (Nm)

F: applied Force (N)

L⦜: Length of lever at right angles to the applied force (m)

• Torque (Moments) in Level 2 Physics will involve Static Systems
• Therefore the Torques are balanced and the Forces are balanced - Newton's Laws of Motion apply to turning forces as well as linear forces
• PhET - Torque Balancing Act simulation

Bridge support forces moments

Torque (Moments anout a point)
Static (unmoving) systems will be used for this section. Therefore all forces, linear and turning, are balanced

Torque

Term 2 Week 1 2019

Homework:

• Ex 4J, p. 143-147 Energy, Work, Power
• Ex 4I, p.137-141, Springs

PhET - Hooke's Law & Springs - HTML

Hooke's Law

Hooke's Law Introduction - Force of a Spring

Hooke's Law F = -kx

Elastic Potential Energy

Intro to Springs and Hooke's Law

Potential Energy Stored in a Spring

How Hard Can You Hit A Golf Ball?