Optics Unit

Question 1

What is Bioluminescence

Answer 1

Bioluminescence is light produced from a chemical reaction by a living thing.
Examples of bioluminescent species includes:
• Blue­green stainer fungi
• other fungi species
• fireflies / lightning bugs
• deep ocean fish species
• algae
• bacteria

Question 2

What is Fluorescent light

Answer 2

Fluorescent light is light emitted by some substances when they are exposed to
electromagnetic radiation.

ex A fluorescent light bulb is a glass tube filled with a small
amount of a gas such as mercury vapour.

Question 3

What is Chemiluminescence

Answer 3

Chemiluminescence is light produced from a chemical reaction without a rise in
temperature.

An example of chemiluminescence is the light produced in glow sticks.

Question 4

what is electric discharge

Answer 4

An electric discharge is a method for producing light in which an electric current
passes through the air or another gas, such as neon.

Lightning is one example of an electric discharge.

Question 5

what is Incandescent light

Answer 5

Incandescent light is light that is produced by an object, such as a metal, that is at a very
high temperature.

Question 6

Electroluminescence

Answer 6

Electroluminescence is a method for producing light in which an electric current passes
through a solid semiconductor.

Question 7

what is Phosphorescent Light

Answer 7

Phosphorescent Light
In fluorescent lights, the phosphor emits light only while it is exposed
to ultraviolet radiation.

Question 8

what is a image and a optical device

Answer 8

a image is a reproduction of a object produced by a optical device like a mirror

a optical device is any technology that uses light

Question 9

What is the law of reflection

Answer 9

Angle of incident=Angle of reflection

Question 10

what is the angle of incident and angle of reflection

Answer 10

angle of incident is the angle between the incident ray and the normal one which is the middle one

and angle of reflection is the angle between the reflected ray and the normal

Question 11

Law of reflection states what

Answer 11

when a light reflects of a surface the angle of incident is equal to angle of reflection

Question 12

what is the vertex of a mirror

Answer 12

the middle point

Question 13

what is the principal axis

Answer 13

imaginary line through the vertex.

Question 14

F is what

Answer 14

the focal point on a diagram

Question 15

what does salt stand for

Answer 15

S - size of the image (bigger or smaller)
A - Attitude of the image (facing up or facing down)
L - Location of the image (infront of mirror, behind mirror)
T - Type of image (real or virtual)

Question 16

what is a ray model

Answer 16

a diagram of rays travelling from the source outwards in all directions

Question 17

what is transparent

Answer 17

1. Transparent - these absorb and reflect very little light, light is transmitted
   very easily through these objects. Examples are clear glass and clear plastic.

Question 18

what is translucent

Answer 18

Translucent - these transmit some light, but you cannot see what is on the
other side of the object. Example is a frosted window.

Question 19

what is opaque

Answer 19

Opaque - objects absorb and reflect light and nothing is transmitted.
Example desk, floor.

Question 20

do incoming rays travel parallel to each other?

Answer 20

yes

Question 21

regular reflection vs diffuse reflection

Answer 21

regular -The light rays strike a smooth surface and reflect in the same direction,
staying parallel to one another.

diffuse-· Light rays strike an uneven surface (rough) and are scattered in
different directions.

Question 22

what is color

Answer 22

color is how our brain interprets light

Question 23

light is made up of what

Answer 23

different wave lengths

Question 24

what do wave lengths do

Answer 24

wave lengths are not colored, they produce sensation of color in our brain, different wave lengths of light give us color

Question 25

the electromagentic spectrum goes from left to right from

Answer 25

radio waves,microwaves,infared waves,ultraviolet waves,x rays,gama waves.

Question 26

radio waves 
microwaves
infrared waves
ultraviolet waves
X-rays
Gamma rays

Answer 26

radio waves are the longest wave length and lowest frequency waves
microwaves have shorter wavelengths than radiowaves but carry more energy
infrared waves are shorter then microwaves and experienced as heat
ultraviolet waves comes from sun and the stars and are shorter then infrared

X-ray high radiation energy that can penetrate human tissue
gamma ray
extremely high energy

Question 27

what is a fibre optic

Answer 27

thin transparent glass tube that can transmit light around corners.

Question 28

what property of wave length determines the colour of the light

Answer 28

the length of the wave
longest wave length color - red
shortest is blue or violet light

Question 29

what is the cornea

Answer 29

transparent layers of tissue over eyes that refracts light into your eye

Question 30

what is the pupil

Answer 30

the hole in your eye that lets light to pass

Question 31

iris

Answer 31

the circular muscle around the pupil that controls the amount of light coming through the pupil, it gives eye color

Question 32

retina

Answer 32

the inner lining of the eye that acts as a projection screen

Question 33

lens

Answer 33

over lens is a convex lens, which changes shape so that is allows you to focus on objects that are near or far

Question 34

photoreceptors

Answer 34

photoreceptors absorb light rays so you can see

in the retina

Question 35

what is refraction of light

Answer 35

the way light bends

Question 36

why does refraction happen

Answer 36

it happens due to the changes in the speed of light as it passes through a medium.

Question 37

what is a normal

Answer 37

a line that is drawed 90 degrees to the surface where the light rays cross into

Question 38

what happens to a ray after gone through a object

Answer 38

it increases and the direction changes