Term 2 Week 7 2021

 

• Act 15A, p. 173-176, Particles and Half-Life
• Act 16A, p. 181, Nuclear Reactions
• Act 5A, p,53-54, Pulses and Waves
• Worksheet on Superposition and Reflection
• Act 5B, p. 58, Reflection, Refraction and Diffraction of Waves
• Act 5C, p.63-64, Diffraction and Superposition
• Act 6A, p.69< Plane Mirrors

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

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

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

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?