Light and Optics, Topic 1 Quiz

Light and Optical Systems

• Light is a form of energy that can be seen. This energy can be produced naturally by sources like the sun and stars, or artificially by technologies.

Natural Light Sources

• Natural light sources are not man-made.
• Examples include the sun, stars, and lightning.

Artificial Light Sources

• Artificial light sources are man-made.
• Examples include candles, lamps, and matches.

First Basic Principle of Light

• Light is a form of energy.
• When light reaches a surface, it can be absorbed or transformed into other types of energy.

Types of Energy Transformations

• Electrical: Solar panels or batteries convert light energy into electrical energy.
• Thermal: Cameras can transform light into thermal images, and dark clothes gain thermal energy (heat) from sunlight.
• Chemical: Plants like trees convert light energy into sugar through photosynthesis.

Brightness and Intensity of Light

• Brightness, or intensity, of light indicates the amount of energy a surface receives.

Sources of Light

• Light pollution can be a problem in urban areas.
• Streetlights are now designed to direct light downward to reduce light pollution.
• More energy efficient lights are used to decrease light pollution.

Incandescent Light Sources

• Objects heated to very high temperatures emit visible light.
• Electrical energy transforms to thermal energy, which in turn transforms to visible light energy.
• The majority (95%) of energy from incandescents is released as heat.

Fluorescent Light Sources

• High-energy ultraviolet radiation is absorbed by particles; the particles then emit light. This emission is called fluorescence.
• UV light energy —> particles absorb —> visible light energy
• Fluorescent lights are expensive to produce and hard to dispose of and contain toxic materials.
• They are however more energy efficient because they do not produce thermal energy and are not hot to the touch.

Phosphorescent Light Sources

• Energy is transferred similarly to fluorescent bulbs but phosphorescent particles store energy and release it slowly.
• They continue to glow after the light source is removed.
• UV light energy —> particles absorb —> visible light energy (stored and released over time)

Chemiluminescent Light Sources

• Light is produced from chemical reactions.
• Chemical energy —> visible light energy.
• Example: glow sticks.

Bioluminescent Light Source

• Living creatures produce this type of light.
• Purpose includes: allowing animals to see in dark places like the deep ocean, attracting mates and prey.
• Example: anglerfish mating.

Luminous Objects

• Objects that emit light are called luminous.

Review of Light

• Light is a form of energy.
• Energy can only be transformed or transferred.
• Light sources change different types of energy (e.g., chemical, electrical) into visible light energy.

Light Exploration

• Explore how light interacts with different objects (e.g., mirrors, prisms).
• Investigate light's behavior: bending, shadows, changing the shadow size. Determine how light interacts with various materials.

Ray Model of Light

• A ray is a straight line representing a beam of light.
• Light travels in a straight line.
• Ray diagrams illustrate what happens when light rays encounter different materials.
• Objects affect the size and distance of the shadow.

Behavior of Light

• Transparent: Light passes through with no shadow. Objects are visible through the material. Example: windows.
• Translucent: Some light passes through, some is scattered; a slight shadow may be visible. Images are not clear. Example: frosted glass.
• Opaque: No light passes through; a distinct shadow is formed. Example: wood.

Summary of Light Transmission through Different Materials

• Opaque: Light is mostly absorbed. No transmission through the material.
• Translucent: Some light is transmitted and some is scattered but images are blurred.
• Transparent: Light is transmitted. Images are clear.