8.4 Light

How do we see light?

Light is emitted by certain objects. The light then reflects off another object and is absorbed by our eyes.

How does light behave?

Light behaves mainly like a wave. Different light colours have different wave lengths and frequencies.

What is light made of?

Photons. They carry a fixed amount of energy but have no mass

How does light travel?

In a straight line

At what speed does light travel?

300,000 km/s in a vacuum. Called the speed pf light.

How does light reach our eyes?

A luminous object emits light. This light shines onto other objects, and is then reflected into our eyes, allowing us to see them.

Opaque meaning

do not transmit light (dont let light pass through)

Transparent meaning

transmit all light

translucent meaning

transmits most light

What is the incidence ray?

The light going towards the mirror

What is the line between the incidence ray and reflected ray?

the normal

what is the reflected ray

the light ray that has bounced off a reflecting surface

Law of reflection

the angle of incidence is equal to the angle of reflection

Why does a white snooker ball look white?

Because it reflects all colors of light into the eye.

Why does a red dress appear red?

Because it reflects red light and absorbs other colors.

What does a green filter absorb and transmit?

How do colored filters work?

colored filters absorb certain colors of light and allow others to pass through

What are secondary colors of light?

Magenta, yellow, and cyan are secondary colors, made by mixing two primary colors.

Why does a black snooker ball look black?

Because it absorbs all colors of light and reflects none.

How do we see non-luminous objects?

We see non-luminous objects because light hits the object and is reflected into our eyes.

Why does a red snooker ball look red in white light?

Because it reflects red light and absorbs other colors.

Why does a magenta ball look magenta in white light?

Because it reflects red and blue light, absorbing other colors.

What light do red, blue, and green filters allow to pass?

Red filter allows red light, blue filter allows blue light, and green filter allows green light

What are the primary colors of light?

Red, green, and blue are the primary colors of light.

What happens when different colors of light are mixed?

Mixing light colors produces new colors, such as red + green = yellow, red + blue = magenta, and red + green + blue = white.

What colors are reflected by the frog's skin with red and black markings?

Red parts reflect red light; black parts absorb all colors.

What is the key principle of how we see colors?

we see colors based on the light reflected from objects into our eyes.

What is refraction?

When light passes from one substance into another more dense substance itchanges direction.

What is the interface?

the boundary between the substances

When light passes from a less dense to more dense substance, where does it bend?

it bends towards the normal. angle of incidence > angle of refraction

When light passes from a more dense to less dense substance, where does it bend?

it bends away from the normal. angle of refraction > angle of incidence

What happens when different colors of light are mixed?

Mixing light colors produces new colors, such as red + green = yellow, red + blue = magenta, and red + green + blue = white.

What colors are reflected by the frog's skin with red and black markings?

Red parts reflect red light; black parts absorb all colors.

What is the key principle of how we see colors?

we see colors based on the light reflected from objects into our eyes.