L1 Optics

• Sun gives off large amount of energy called solar radiation.
• Christmas lights are an example of the most efficient form of light.
• Traffic lights are also an example of the most efficient form of light.
• Energy travels through space as electromagnetic waves.
• An electromagnetic wave is energy in the form of a wave associated with electric and magnetic fields.
• Electromagnetic waves can travel through vacuum at speed of light (3 x 10^8 m/s) or a medium.
• Vacuum is empty space.
• Medium is any physical substance that energy can be transferred through.
• The speed of light depends on the medium.
• Air, glass, water, plastic are examples of mediums.
• All waves are invisible, except for visible light, therefore, light is an electromagnetic wave.
• Each wave in the electromagnetic spectrum is assigned a wavelength and frequency.
• Wavelength is the distance between peaks (crests) on waves.
• Peaks are the highest point on a wave.
• Trough is the lowest point on a wave.
• Frequency is the number of complete wavelengths that pass a given point in 1 second (cycles per second).
• Amplitude is the height of a wave.
• Electromagnetic spectrum is the arrangement of all electromagnetic waves according to their wavelength & frequency.
• Ratio between wavelength and energy & frequency: Low energy → longer wavelength → low frequency, High energy → Shorter wavelength → higher frequency.
• Types of electromagnetic waves in electromagnetic spectrum (from low to high frequency) are: Radio waves, Microwaves, Infrared light, Visible light, Ultraviolet (UV) light, X-rays, Gamma rays.
• Each type of electromagnetic wave has different amount of energy and different wavelength.
• Light energy is produced by converting other forms of energy to light energy such as chemical energy, electrical energy, nuclear energy, and thermal energy.
• Incandescence is a category of light sources that produce light when substances are heated to very high temperatures, such as in an incandescent light bulb.
• Luminescence is a category of light sources that produce light when substances are not heated, such as in electric discharge, fluorescence, and phosphorescence.
• Light from incandescence is produced by substances that produce light when heated to very high temperatures, such as in an incandescent light bulb.
• Fuel-burning technologies are a common source of light, converting chemical energy into heat and light.
• Luminescence is a category of light sources that produce light when substances are not heated, such as in electric discharge, fluorescence, and phosphorescence.
• Fluorescence is a category of light sources that produce light when a substance (phosphor) absorbs UV radiation and immediately changes it to visible light, making it very efficient and lasting longer.
• Phosphorescence is a category of light sources that produce light when substances (phosphor) absorb invisible UV radiation, changes it to visible light, lasting over a longer period of time than fluorescence.
• Chemiluminescence is a category of light sources that produce light from a chemical reaction between two chemicals, converting chemical energy into light energy.
• Bioluminescence is a category of light sources that produce light in a chemical reaction in living organisms, occurring in living things to scare predators, lure prey, attract mates.
• Light-Emitting Diode (LED) is a type of light source that allows electric current to flow in only one direction using semiconductors (silicon), saving energy, lasting longer, and staying cooler than all other lightbulbs.
• All types of electromagnetic waves travel at same speed (300,000 km/s) or speed of light in space.
• Visible light is any electromagnetic wave that human eye can see.
• Visible light can be separated into different colors: ROY G BIV (red is lowest frequency, violet is highest frequency).
• Visible spectrum is a continuous sequence of colors that target forms visible white light.
• Visible white light is when all waves are seen together, it makes white light.
• When white light is shone through prism, white light is broken apart in visible light spectrum.
• Natural sources of light include the Sun and fireflies.
• Objects can be seen because light enters your eyes from all objects.