unit 5 ns5

HEAT AND LIGHT

Thermal energy always travels from a hotter

object to a colder one. Some materials transfer

thermal energy easily. They are good

conductors. Materials that dont`t transfer

thermal energy easily are called insulators.

CONDUCTION

When two objects

are in contact,

thermal energy is

transferred from one

object to the other

CONVECTION

Thermal energy

travels through a gas

or a liquid by

convection.

RADIATION

Thermal energy can

be transferred

through space by

electromagnetic

waves.

MELTING

Solid Liquid

EXPANSION

Materials expand when

receive thermal energy

EVAPORATION

Liquid Gas

CHEMICAL CHANGES

Thermal energy can cause

permanent changes(example: when we cook food)

Thermal energy causes changes in the state of

some materials

Light is radiation that we can see with our eyes.

Light travels in straight lines.

Objects react to light in different ways:

Transparent

It doesn`t block

light

Translucent

It blocks some

light

Opaque

It blocks the light

completely

REFLECTION

Some objects, like

mirrors, change the

direction of the light.

The mirrors reflect

the light.

REFRACTION

When light pass through

some transparent

substances (water) it

changes direction

slightly.