Light Types and Reflection Quiz

Light Types and Examples

• Incandescence: Light produced by heat. Example: Lava
• Electric Discharge: Electrons transfer between objects. Example: Lamp.
• Phosphorescence/Fluorescence: Light emitted after absorbing energy from a light source. Example: Glow-in-the-dark toys
• Light-Emitting Diodes (LEDs): Electrical current through a semiconductor produces light. Example: LED light strips

Plane Mirrors and Reflection

• Plane Mirror: Flat surface creating virtual images.
• Incident Ray: Light ray striking a surface.
• Reflective Ray: Light ray bouncing off a surface.
• Angle of Incidence: Angle between incident ray and the normal.
• Angle of Reflection: Angle between reflected ray and the normal.
• Normal: Imaginary line perpendicular to surface at the point of impact.
• Law of Reflection: The angle of incidence equals the angle of reflection.

Characteristics of Images

• Size: Comparison of image size to object size.
• Orientation: Upright or inverted image.
• Type: Real or virtual image.
• Location: Position of image relative to the object.

Mirror Types and Uses

• Concave Mirror: Focal point and center of curvature in front. Light converges at focal point. Use: Telescopes
• Convex Mirror: Focal point and center of curvature behind. Light diverges after reflection. Use: Car side mirrors (wider field of view)

Refraction

• Refraction: Bending of light as it moves from one medium to another, due to change in speed.
• Index of Refraction: Measures how much light bends when entering a material. Represents the degree of bending.
• Types of Refraction: Natural (e.g., in atmosphere) and Artificial (e.g., in lenses).
• Critical Angle: Angle of incidence where light entering a less dense medium is reflected rather than refracted. For total internal reflection to occur, the first medium must have a higher index of refraction than the second.
• Total Internal Reflection: Light reflection when it moves from a denser to a rarer medium at an angle greater than the critical angle. Used in fiber optics.
• Examples of Refraction:
  • Light before sunrise: Sunlight bending in the atmosphere.
  • Apparent depth: Objects in water appearing shallower.
  • Mirages: Illusions in air layers of varying temperature.
  • Rainbows: Light refracting and reflecting in raindrops.
• Fiber Optics: Use total internal reflection for light transmission.

Lenses

• Convex Lens: Thicker middle, converging parallel light rays to a focal point.
• Concave Lens: Thinner middle, diverging parallel light rays.

Parts of the Eye and Vision

• Pupil: Controls light entering the eye.
• Iris: Regulates pupil size.
• Retina: Receives light, converts to electrical signals.
• Lens: Focuses light onto the retina.
• Rods: Detect light/dark, low light vision.
• Cones: Detect color, detailed vision in bright light.

Refractive Errors

• Nearsightedness: Clear near vision, blurry far vision. Cause: Eyeball too long, or cornea too curved. Fix: Concave lenses.
• Farsightedness: Clear far vision, blurry near vision. Cause: Eyeball too short, or cornea too flat. Fix: Convex lenses.

Color Mixing

• Red + Green = Yellow
• Red + Blue = Magenta
• Blue + Green = Cyan
• Red + Blue + Green = White
• Blue object in yellow light appears green
• Cyan object in green light appears green
• Magenta object in green light appears black
• Cyan object in yellow light appears green