physics day 3

Waves

  • Overview of Topics

    • Wave pulses

    • Sinusoidal Waves

    • Interference and Diffraction

    • Wave model of light

Wave Pulses

Understanding Oscillations and Waves

  • Oscillations:

    • Involve individual entities that vary periodically over time (e.g., back and forth)

    • Examples include:

      • Pendula

      • Molecular vibrations

      • Heartbeats

      • Firefly lights

      • Voltage in power grids

      • Some types of enzyme production

  • Waves:

    • Collections of individual entities that vary together in time and space, which may or may not be periodic

    • Examples include:

      • Light

      • Sound

      • Water waves

      • Earthquakes

      • Electrochemical signals in neurons

Differences between Oscillations and Waves

  • Oscillations operate on individual elements, whereas waves represent collective behavior among multiple elements.

A Moving Pulse

  • Study a wave pulse and its motion

Sketching the Movement

  • Diagram Requirements:

    • Show the y position of a bead as a function of time.

Further Illustration of Moving Pulses

  • Visualize wave form changes over time by sketching the initial wave followed by its form at later intervals.

  • Sketch Sequence:

    • Initial wave pulse

    • Wave pulse after a short duration

    • Wave pulse a bit later

Bead Movement in a Pulse

  • Illustrate how individual beads in a pulse move from one position to another

  • Position Changes:

    • Indicate the direction and extent of movement through vertical arrows from initial to new positions of the wave pulse.

Observations of Wave Pulses

  • Snapshot Analysis:

    • Discuss how a point on the string shows its y-displacement, y-velocity, x-velocity, and y-force at different times visually represented by images.

Reflection at Wave Ends

  • Fixed End:

    • Discuss behaviors of waves when encountering fixed ends (e.g., bounce back upside down).

  • Loose End:

    • Discuss behaviors of waves when encountering loose ends.

Interference and Wave Combination

  • Wave Interference:

    • Understand how two or more wave pulses interact, including condition where they overlap perfectly to reinforce.

The Big Picture of Waves

  • Key Considerations:

    • Wave shape (f(x,t)), wave speed (v), and local medium speeds

    • Understand how wave shapes combine

    • Wave Relationships:

      • Wavelength (λ), frequency (f), and speed (v) correlate in sinusoidal waves

Controlling Wave Speed

  • Examine factors influencing wave pulse speed:

    • Hand motion frequency and amplitude

    • String density and tension adjustments

Sinusoidal and Standing Waves

  • Develop an understanding of the equations governing sinusoidal waves, including definitions for key parameters like k, λ, ω, f, and T

Calculating Wave Speed

  • Connect graphical information to wave speed calculations in practice, specifically using oscillation tests.

Resonant Frequencies

  • Discuss how resonant frequencies relate to wave patterns using small amplitudes.

Two-Slit Interference

  • Understand how light behaves when traveling through slits, focusing on the differing results than predicted by standard ray models.

Characteristics of Light Waves

  • Explore the wave spectrum of light, providing details on wavelength and frequency differences across the electromagnetic spectrum.

  • Spectrum Chart:

    • Ranges from radio waves to gamma rays, detailing energy levels and wavelengths from visible light (400-700 nm) to high-energy UV rays.

Comparison of Color and Wavelength

  • Examine how changes in wavelength affect interference patterns, considering how moving closer affects observed patterns.

Interaction of Photons

  • Explain absorption and emission concepts in the light-matter interaction, emphasizing their resonance with specific energies.

Energy Quantization

  • Discuss how energy levels in atoms are quantized and how this leads to photon interactions during absorption and emission.