What do you know about light?

Think – Pair - Share

Light can be

Luminous – object that emits (gives off)

their own light. (ex. Sun)

or

Nonluminous – object that do not emit light, but only reflect light from other sources.

Light from Incandescence

• The process of emitting light because of a high temperature is incandescence.

• Example: Incandescence light bulb

Light from Phosphorescence

• The process of emitting light for some time after receiving energy from another source.

• Example: Glow in the dark watch

Light from Electric Discharge

• The process of emitting light because of electricity passing trough a gas .

• Example: Neon sign

Light from Fluorescence

• The process of emitting light while receiving energy from another source.

• Example: fluorescent light bulb

Light from Chemiluminescence

• The process of changing chemical energy into light energy with little or no change in temperature.

Light from Bioluminescence

• Some living things can make themselves luminous using chemical reaction similar to chemiluminescence.

• Example: Fireflies, glow worms

Light

Light can be: • Natural – bioluminescence, stars, sun, moon • Electric – incandescent light bulbs, flashlights

and electroluminescence (LED) • Chemical – chemiluminescence (glow sticks),

fluorescence (fluorescent light bulbs) and phosphorescence (glow in the dark materials)

• Combustion-based – candles, fire, torches • Nuclear

What are some technologies based on properties of light?

• microscope• telescope• periscope• binoculars• fiber optics• camera

• prescription contact lenses

• laser• movie projectors• overhead projectors• etc.

The History of Light

• Pythagoras (born between 580 and 572 BC, died between 500 and 490 BC)

• A Greek mathematician and philosopher.  

• He believed that beams of light were made up of tiny particles.

• When these beams of light came from objects and reached the eye, they carried information about the object to the eye.

Albert Michelson (1852-1931)

• An American physicist known for his work on the measurement of the speed of light.

• In 1907 he received the Nobel Prize in Physics, the first American to receive the Nobel Prize in sciences.

Early Technologies

• One of the earliest technologies involved using light to improve vision. This was a curved piece of glass which enlarged print.

Today we call this a magnifying glass

• This technology eventually led to glasses.

Then (1200) Now

Anton van Leeuwenhoek (1632-1723)

• He is commonly called the “Father of Microbiology”

• He was the first person to observe and describe single celled organisms.  

Microscope• He created over 400 types of

microscopes after he discovered that he could increase the magnifying power of a lens by increasing its curvature.

1st compound microscope

Leeuwenhoek microscope

NowThen

Galileo Galilei (1564-1642)

• He made his own lenses which he used to build a telescope to magnify objects in space.

• He discovered four of Jupiter’s moons.

Galileo’s early telescope