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waves slideshow 19-39 Telephones and Light

Telephones and How They Work

  • Evolution of Telephones

    • Telephones have undergone significant changes over the last 100 years.

  • How Does a Telephone Work?

    • Research and discovery:
    • Locate reliable videos or articles explaining the mechanics of traditional telephones (not including cell phones).
    • Discuss the role of the microphone and speaker in a telephone.
    • Microphone Function: Converts sound waves into electrical signals.
    • Speaker Function: Converts electrical signals back into sound waves.

Electromagnetic Spectrum

  • Understanding the EM Spectrum

    • The electromagnetic (EM) spectrum encompasses all types of light.
    • Only visible light is detectable by the human eye.

  • Frequency and Wavelength

    • Low Frequency: Detected in longer wavelengths.
    • High Frequency: Detected in shorter wavelengths.

  • Key Components of the EM Spectrum

    1. Gamma Rays: Smallest wavelength and highest frequency. Most dangerous to humans.
    2. Visible Light: Part of the spectrum that humans can see.
    3. Ultraviolet Light: Just above violet, harmful to skin.
    4. Radio Waves and Microwaves: Used for telecommunications.
    5. X-rays: Visualize broken bones.

Properties of Light and Matter

  • How Matter Affects Light

    • Matter can:
    1. Transmit light.
    2. Absorb light (e.g., apple reflects red).
    3. Scatter light (e.g., fog).
    4. Refract (bend) light (angle depends on material).
    5. Reflect light (e.g., mirrors).

  • White Light

    • Composed of all colors of the rainbow: ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet).
    • Each color has a unique wavelength (Red = longest wavelength, Violet = shortest).
    • A prism can refract white light to show all colors.

Understanding Color Perception

  • How We See Colors

    • Example of an apple:
    1. White light hits the apple.
    2. The apple absorbs all colors except red; reflects red.
    3. Light passes through the pupil into the retina, converting light to electrical energy sent to the brain.

  • Color Absorption

    • If an object absorbs all wavelengths, it appears Black.
    • If it reflects all wavelengths, it appears White.

Eye Functionality

  • How the Eye Works

    • Light energy travels through the cornea, bends, and adjusts according to light levels.
    • The lens focuses light on the retina where it is transformed into electrical signals and sent to the brain.

  • Vision Issues

    • Nearsightedness: Light focuses in front of the retina.
    • Farsightedness: Light focuses behind the retina.
    • Corrective lenses:
    • Concave lenses for nearsightedness.
    • Convex lenses for farsightedness.

Lenses and Corrective Vision

  • Role of Lenses

    • Glasses help focus light correctly on the retina, improving visual clarity.
    • Magnifying glasses bend light to enlarge objects.

  • Laser Eye Surgeries

    • Procedures like LASIK reshape the cornea to fix vision problems.

Light Reflection and Refraction

  • Mirror and Lens Interaction
    • Mirrors reflect light while lenses refract it.
    • The design of objects (like a spoon) can alter perceptions due to reflection/refraction effects.

Light Comprehension Check

  • Assessment Questions

    1. What color if all wavelengths of white light reflect?
    2. What color if all wavelengths are absorbed?
    3. Which color has the lowest and highest frequency?
    4. Does light travel as transverse or longitudinal waves?
    5. What type of wave is light, mechanical or electromagnetic?
    6. Describe the pathway light takes in the eye.
    7. How do nearsighted and farsighted people differ in eye length?
    8. What causes cataracts?
    9. Differentiate between how lenses and mirrors work with light.

  • Answer Key

    1. White
    2. Black
    3. Red (lowest), Violet (highest).
    4. Transverse
    5. Electromagnetic
    6. Pupil, Lens, Retina
    7. Long, Concave
    8. Lens
    9. Refract, Reflect