Physics

Question 1

Type 2

Non-luminous

Answer 1

An object that does not give off its own light (moon)

Question 2

Incandescence

Answer 2

Light given off due to high temperatures

Question 3

Fluorescence

Answer 3

Chemical that gives off light when hit by invisible high energy waves-uv Rays hit the fluorescent coating and turn into visa me light

Question 4

Phosphorescence

Answer 4

Phosphorus absorbs the light rays and gives off visible light. -bedroom stars

Chemicals that give off light when hit by high energy light waves, and stay luminous for long periods of time. (Glow in the dark)

Question 5

Chemiluminesence

Answer 5

Chemical reactions that give off light with next to no heat (glow sticks)

Question 6

Bioluminescence

Answer 6

When living things produce light (fire fly)

Question 7

Triboluminescent

Answer 7

When certain crystals (sugar) are scratched , crushed or rubbed together light can be produced (life savers)

Question 8

LEDs

Answer 8

Light emitting diodes

Question 9

How LEDs work

Answer 9

• small lights that do not get too hot when they give off light.
• they are made of small crystals of silicon that light up when electricity flows in the proper direction,

Question 10

Why LEDs are the best

Answer 10

1- DONT waste energy for heat
2- don’t contain mercury
3- last along time

Question 11

Lasers

Answer 11

Light amplification by stimulated emission of radiation

Question 12

Use for lasers

Answer 12

• very bright (intense)
• the light is all the same colour (electromagnetic waves of the same energy level)
• the light stays together as a beam (unison)
• scanners, exrays, phones, computers,

Question 13

What is light

Answer 13

• a wave of electric and magnetic fields
• wave of energy- shown to be particle like in nature
• energy can vibrate atoms and electrons which can release this energy as visible through colour

Question 14

Fusion

Answer 14

Tremendous amount of energy
Light is needed for life
Emitted in all directions in a straight line
Speed- 300 000 000 meters per second (faster than sound)

Question 15

What does rectilinear propagation mean

Answer 15

Light travels very fast in a straight line

Question 16

Sharp shadows the objects is

Answer 16

Farther away from the source. It is small compared to the source

Question 17

Fuzzy shadows the objects is

Answer 17

Close to the light source. Object is small compared to the source.

Question 18

What happens when light strikes an object: ( 3 ways)

• transparent
• translucent
• opaque

Answer 18

1) reflected 2) absorbed 3) transmitted
- all light rays pass through (glass)
- some light rays pass through (frosted glass)
- no light can go through (card board)

Question 19

Salt

Answer 19

Size - smaller, larger, same
Attitude - upright, inverted, latterly inverted
Location - at c, beyond c… Behind mirror
Type - virtual, real

Question 20

Regular specular reflection of light:

Answer 20

On shinny surfaces, light tends to reflect following the law of reflection. A clear image is seen

Question 21

Diffuse reflection of light:

Answer 21

On rough surfaces the reflection waves become irregular. The light tends to spread out in all directions and no clear image is formed.

Question 22

Type 1

Luminous

Answer 22

An object that gives off its own light (candle, fire, light bulb)