Grade 10 Optics Review - Key terms

only stuff that I need extra help studying

electromagnetic waves from lowest to highest frequecy

radio, microwave, infrared light, visible, x-rays, gamma rays

Why is an incandescent bulb a very inefficient light source?

Only 5% of the electrical energy converts to light energy, the rest is wasted as thermal energy

Describe the difference between a real image and a virtual image.

Real images are produced when the reflected/refracted rays ACTUALLY meet. Virtual images are produced when the reflected/refracted rays do not meet and our brains imagine the image being created 

Incandescence

Produced by heating a material, mostly a metal filament like tungsten until it glows. (incandescent light bulbs)

Electric Discharge

Light is produced when electricity passes through gas exiting the gas particles and causing them to emit light. (neon lights)

Phosphorescence

Materials absorb light energy and slowly release it over time as visible light. (glow in the dark products)

Fluorescence

• Produced when UV light is absorbed and almost immediately re-emitted as a different coloured light. (highlighter)

Chemiluminescence

light produced from a chemical reaction. (glowsticks)

Bioluminescence

Chemical reaction within a living creature. (jellyfish)

LED

LEDs produce light using a process called electroluminescence (the process where material emits light).

Triboluminescence

When a material is mechanically stressed through stretching, rubbing or crushing (cutting diamonds)

Fusion

2 light nuclei merging into one larger nucleus. Usually UV light (sun and stars)

What is refraction and why does it happen?

the bending of a wave, like light, as it passes from one medium to another. This bending occurs because the wave's speed changes as it enters the new medium.

If medium 2 is more dense than medium 1, refracted ray bends…

towards the normal

if medium 2 is less dense than medium 1, refracted ray bends…

away from the normal

What is total internal reflection and why does it happen?

When light moves to a less dense medium, the angle of incidence is greater than the critical angle.