light and optics

Question 1

how does the human eye see

Answer 1

light passes through the cornea. Some of this light enters the eye through an opening called the pupil. Next, light passes through the lens. When light hits the retina, special cells called photoreceptors turn the light into electrical signals. These electrical signals travel from the retina through the optic nerve to the brain. Then the brain turns the signals into the images you see.

Question 2

nearsightedness

Answer 2

you can see objects near to you clearly, but objects farther away are blurry.

Question 3

what causes nearsightedness

Answer 3

It occurs when the shape of your eye causes light rays to bend (refract) incorrectly, focusing images in front of your retina instead of on your retina.

Question 4

how to fix nearsightedness (what lens used)

Answer 4

glasses, contact lenses, eye drops and surgery. uses concave lenses

Question 5

farsightedness

Answer 5

you can see distant objects clearly, but objects nearby may be blurry.

Question 6

what causes farsightedness

Answer 6

it occurs when light is not refracted properly through an uneven, less smooth cornea or lens. It is a type of refractive error. The light rays focus at a point behind the retina.

Question 7

how to fix farsightedness (what lens used)

Answer 7

glasses, contact lenses, eye drops and surgery. uses convex lenses

Question 8

what is refraction

Answer 8

The bending of light that travels from one medium to another. Light changes speed when it needs to move through materials with different densities.

Question 9

give an example of refraction

Answer 9

Looking at an object through a jar of water.

Question 10

what is reflection

Answer 10

The process in which light strikes a surface and bounces back off that surface.

Question 11

give an example of reflection

Answer 11

Mirrors allow you to see an image of yourself (smooth surface)
Reading a textbook (rough surface)

Question 12

Laser eye surgery (light technology)

Answer 12

An advanced laser makes subtle adjustments to the shape of the surface of your eye (the cornea), correcting its tiny imperfections and making your vision clearer and sharper.

Question 13

fiber optics (light technology)

Answer 13

are long, thin strands of carefully drawn glass about the diameter of a human hair. Fiber optics is the technology used to transmit information as pulses of light through strands of fiber

Question 14

light bulb (light technology)

Answer 14

Electricity flows through a thin tungsten wire in the light bulb called the filament. As a result of this resistance, the filament heats up and starts glowing, converting electrical energy to light energy.

Question 15

cost of lighting

Answer 15

How much will it cost to leave a 60 W bulb on for 10 h if
electrical energy costs 8¢/kW•h?
1. Convert 60 W to kilowatts by dividing by 1000.
60 W ÷ 1000 = 0.06 kW
2. Calculate the number of kilowatt hours by multiplying the power
(in kW) by the number of hours.
Number of kW•h = 0.06 kW × 10h = 0.6 kW•h
3. Calculate the cost of leaving the light on for 10 h by multiplying
the number of kilowatt hours by the cost per kilowatt hour.
Cost (in cents) = Amount of energy (in kW•h) × Unit price
(in¢/kW•h)
Cost = 0.6 kW•h × 8¢/kW•h = 4.8¢

Question 16

visible light spectrum

Answer 16

• Natural light (yellow and green) tells your body that it is time to be awake
• Red light helps your body to relax (night mode on your phone)
• Blue light from your computer and fluorescent lights can lead to eye strain and macular degeneration. Blue light glasses block blue light and allow other colour waves to enter you eyes.

Question 17

convex

Answer 17

shaped curved outward

Question 18

convex function/example

Answer 18

convex glasses fixes farsightedness

convex mirrors are useful security devices.

Question 19

concave

Answer 19

shaped curved inward

Question 20

concave function/example

Answer 20

concave glasses fixes nearsightedness

concave mirrors are useful for adding make-up or shaving

Question 21

telescope

Answer 21

a optical instrument for viewing distant objects by means of the refraction of light rays through a lens or the reflection of light rays by a concave mirror

Question 22

telescope example

Answer 22

refracting telescope or reflecting telescope

Question 23

microscope

Answer 23

an instrument that makes an enlarged image of a small object, thus revealing details too small to be seen by the unaided eye.

Question 24

microscope example

Answer 24

compound light microscope or stereoscopic microscope

Question 25

binocular

Answer 25

providing a magnified stereoscopic view of distant objects, consisting of two similar telescopes, one for each eye, mounted on a single frame.

Question 26

binocular example

Answer 26

monocular binocular or roof prism binocular

Question 27

light transmission

Answer 27

When light travels through a medium such as glass without being reflected absorbed or scattered.

Question 28

light transmission example

Answer 28

light passing through an object

Question 29

absorption

Answer 29

a substance captures and transforms energy.

Question 30

absorption example

Answer 30

black pavement which absorbs energy from light.

Question 31

historical theory on light

Answer 31

Wave theory of Huygens
Compared light to sound waves.
-However, that light can travel through a vacuum unlike sound because it is transparent and able to fill all space.

Question 32

compare the human eye and dolphin eye

Answer 32

A dolphin eye is made to see clearly underwater, while the eye of a human can see underwater blurry because the optical power of a human isn’t strong as a dolphins optical power in the eyeball.
A dolphin has 2 cells in their eye while humans have around 137 million rod cells and cone cells. Rod cells and cone cells help us see and help us see different colours from varying distances.
Dolphins can see two different directions while humans can only see the same direction because the distance between the humans’ eyes isn’t far apart and is very close, but dolphins can see two different directions because their eyes are placed with a big distance between them. Dolphins can only see a limited amount of colours while humans can see about 10 million different colours.

Question 33

identify current theories about light

Answer 33

Wave theory of Huygens
- Compared light to sound waves.
-However, that light can travel through a vacuum unlike sound because it is transparent and able to fill all space.
-Confusing right?
2. Corpuscular Theory of Light (Newton)
-In 1690 Newton proposed the corpuscular theory of light. He believed that light was shot out from a source in small particles, and this view was accepted for over a hundred years.
*Both theories tried to explain reflection and refraction.
Quantum Theory of Light
-Max Planck in 1900 combined wave theory and particle theory, and proposed that light can sometimes act like a particle and sometimes act like a wave.