Light and Geometric Optics Mind Map

Medium is any physical substance through which energy can be transferred. It acts as a carrier for the transmission of energy.

There are 3 ways energy can be transferred. The three ways are CONDUCTION, CONVECTION, radiation. Heat energy can be transferred by either conduction or convection. Light energy is transferred through radiation.

Both convection and conduction require a medium for transmission and both methods involve particles to transfer heat.

Light on the other hand does not require a medium for transmission.

DIRECT CONTACT

Conduction occurs when two objects at different temperatures are in direct contact with each other. Heat flows from the warmer to the cooler object until they are both at the same temperature.

Conduction occurs most often in solids. Solids are better conductors than liquid and gas.

EXAMPLE: heat transfer by conduction occurs when you touch something that is hotter or colder than your skin, something we do on a daily basis where we experience conduction is when you wash your hands in warm or cold water.

ELECTROMAGNETIC WAVES

Radiation is a method of heat transfer that does not rely upon any contact between the heat source and the heated object. No mass is exchanged and no medium is required; does not need any help of matter with the transfer.

Electromagnetic waves is a wave that has both electric and magnetic parts, that does not require a medium, and travels at the speed of light.

Radiation is the energy that is transferred as electromagnetic waves, such as visible light and infrared waves.

EXAMPLE: when we feel the heat from the sun's rays, even though they don't touch us. We feel heat as waves can pass through the vacuum of space where there are no particles.

THE COLOURS OF VISIBLE LIGHT ARE:

RED, ORANGE, YELLOW, GREEN ,BLUE ,INDIGO, and VIOLET

Characteristics of light:

• colour
• contrast
• hardness
• direction
• intensity
• brightness
• temperature

Phosphorescence is the process of producing light by the absorption of ultraviolet light resulting in the emission of visible light over an extended period of time.

Practical applications of phosphorescence light are objects that glow in dark, such as the dials on some wristwatches and clocks, and glow-in-the-dark stickers and toys.

Fluorescence occurs

when an object absorbs ultraviolet light and immediately releases the energy as visible light

Practical application of light from fluorescence are laundry detergent, highlighters, and fluorescent lights.

Chemiluminescence is the production of light as a direct by-product of a chemical reaction, with little or no heat.

Practical application of light from Chemiluminescence are glow sticks and light sticks.

Bioluminescence occurs

when chemiluminescence occurs in living organisms. It is the production of light in living organisms as the result of a chemical reaction with little or no heat produced

Practical applications of bioluminescence are bacteria, fungi, fish, fireflies, glow worms, marine invertebrates

Triboluminescence is the

production of light when certain crystals are scratched, crushed or rubbed.

Unlike other methods of producing light, triboluminescence does not appear to have any practical application at this time. (textbook)

LED is an electronic device that allows an electric current to flow in one direction. Light is produced as a result of an electric current flowing in semiconductors

Practical applications of LED are street lights and decoration lights

Lasers are used in many ways:

• cutting metals
• drilling
• space communication
• barcode readers
• welding
• burn a hole through steel in a manufacturing process
• laser surgery (hospitals for some small surgeries)
• computer devices such as laser mouse, laser presentation, CDs and DVDS
• toys
• robotics, especially in image processing and calculating distances (measure the Earth-Moon distance)