Light and Optics - Grade 8

What is light? 

A FORM OF ENERGY 

What is the difference between light absorption, light transmission, and light reflection? 

Light absorption is when the light gets absorbed by the surface it hits. Light transmission is when light transmit through the object. Light reflection is when light reflects off a surface.

What is the law of reflection? 

The law of reflection is when the angle of incidence is equal to the angle of reflection.

How does light behave when it strikes a concave mirror? A convex mirror? 

 

When light strikes a concave mirror the light rays cave in together. When light strikes a convex mirror light rays bounce outwards from the mirror. Convex mirror example: Shopping isles. Concave mirror example: truck to be able to see from behind. 

How does light behave when it strikes a concave lens? A convex lens? 

When light rays strike a concave lens, the light converges together but go out once on the other side. When light rays strike a convex lens, the light rays diverge from inside but once outside the lights converge to a focal point. 

What is a real image? A virtual image?

A real image is formed by the actual intersection of light rays whereas a virtual image is formed by the imaginary intersection of light rays. 

What is refraction? How does it work? 

Refraction is when a light ray passes through a glass surface and bends through towards the normal or away from it. 

Myopia vs. Hyperopia 

Myopia: Can’t See Far Away and the eyeball is too long so light converges before retina. 
Hyperopia: Can’t See Close and eyeball is too short so light converges after retina. 
 

Retina?

Tissue at back of the eye where image is formed?

Cornea?

Transparent tissue that covers the iris and pupil. Majority of focusing happens here.

Sclera?

An opaque tissue that surrounds the cornea and helps maintain the shape of the eye. White region around eye. 

Lens?

A clear structure behind the pupil that refracts and focuses light.

Virtuous Humour?

Gel-like substance that fills the space between the lens and the retina within the eye.

Optic Nerve?

Nerve that transmits electrical signals from the eye to brain. Where blind spot is.

Cone Cells?

Allow us to detect colour.

Rod Cells?

Allow us to detect shapes and movement especially in low light conditions.

Aqueous Humour?

Nourishes the lens and maintains pressure within the eye. 

Ciliary?

Controls the shape of the lens.

What types of lenses can be used to correct hyperopia? Myopia? 

Concave lenses correct myopia and convex lens correct hyperopia.  

What are some vision enhancing technologies?

Glasses and lenses are vision enhancing technologies so are telescopes. Laser surgery also enhances vision.

Human Eye	Camera	Similarities	Difference
Lens	Lens	-Both are for focusing light.  -Convex lens	Eye Controlled by ciliary muscle    Lens in camera moves, or you switch the lenses.
Iris	Diaphragm	Controls the opening	Also involves shutter speed. How much light enters. Can manually change the shutter speed and diaphragm.
Pupil	Aperture	Is the opening which allows light in	Mechanical vs. muscular
Retina	Film or Digital Sensor	Capture light for the image	Image produce on film vs. Image created through electrical impulses being sent to brain.