1. THERMAL ENERGY TRAVELS THROUGH A GAS OR THROUGH A LIQUID RADIATION
UNIT 5- HEAT AND LIGHT.
HOW DOES THERMAL ENERGY TRAVEL THROUGH OBJECTS?
THERMAL ENERGY ALWAYS TRAVELS FROM A HOTTER OBJECT TO A COLDER ONE
CONDUCTION
WHEN TWO OBJECTS ARE IN CONTACT, THERMAL ENERGY IS TRANSFERRED FROM ONE OBJECT TO ANOTHER.
CONVECTION
THERMAL ENERGY TRAVELS THROUGH A GAS OR THROUGH A LIQUID
RADIATION
THERMAL ENERGY CAN BE TRANSFERRED THROUGH SPACE BY ELECTROMAGNETIC WAVES.
FOR EXAMPLE: THERMAL ENERGY FROM THE SUN, IS TRANSFERRED BY RADIATION.

2. CONDUCTORS AND INSULATORS
SOME MATERIALS TRANSFER THERMAL ENERGY EASILY.
FOR EXAMPLE:
METAL
INSULATORS:
SOME MATERIALS DON´T TRANSFER THERMAL ENERGY EASILY
WOOD.

3. CHANGES IN STATE OF SOME MATERIALS
MELTING:
WHEN A SOLID RECEIVE THERMAL ENERGY, IT CHANGES INTO A LIQUID.
FOR EXAMPLE: ICE, CHOCOLATE.
EVAPORATION:
WHEN THERMAL ENERGY IS APPLIED TO A LIQUID. IT CHANGES INTO A GAS.
FOR EXAMPLE:
WATER IN THE STOVE
CHEMICAL CHANGES:
THERMAL ENERGY CAUSES CHEMICAL CHANGES.
WHEN WE MAKE A CAKE, WE MIX EGGS, FLOUR AND SUGAR AND GET A LIQUID. THERMAL ENERGY CHANGES THIS LIQUID MIXTURE INTO A SOLID CAKE. BUT WE CAN´T CHANGE THE CAKE BACK INTO EGGS, FLOUR AND SUGAR AGAIN.

4. WHAT IS LIGHT ?
LIGHT IS RADIATION THAT WE CAN SEE WITH OUR EYES. WITHOUT LIGHT, WE WOULDN´T
BE ABLE TO SEE.
LIGHT PHENOMENA:
OBJECTS REACT TO LIGHT IN DIFFERENT WAYS:
TRANSPARENT: THE OBJECT DOESN´T BLOCK THE LIGHT. FOR EXAMPLE: GLASS.
TRANSLUCENT: THE OBJECT BLOCKS SOME LIGHT, BUT SOME LIGHT PASSES THROUGH IT.
FOR EXAMPLE: A CURTAIN
OPAQUE: THE OBJECT BLOCKS THE LIGHT COMPLETELY. FOR EXAMPLE: A DOOR. OUR BODY.
LIGHT TRAVELS IN STRAIGHT WAVES. WHEN WE PUT AN OPAQUE OBJECT IN FRONT OF LIGHT,
WE CAN SEE A SHADOW BEHIND THE OBJECT. LIGHT IS BLOCKED BY THE OBJECT, AND FORMS
THE SHADOW.

5. BASIC LAWS OF LIGHT REFLECTION REFRACTION
LIGHT ENERGY BOUNCES OFF A SURFACE AND IT CHANGES THE DIRECTION.
FOR EXAMPLE:
WHEN LIGHT ENERGY HITS A MIRROR, IT IS REFLECTED.
WHEN LIGHT PASSES THROUGH SOME TRANSPARENT SUBTANCES, LIKE WATER, THE LIGHT ENERGY CHANGES DIRECTION SLIGHTLY.
FOR EXAMPLE: A PEN IN A GLASS WITH WATER.
REFLECTION
REFRACTION

6. HOW IS LIGHT TRANSFORMED INTO HEAT?
WHEN LIGHT HITS AN OBJECT, SOME OF THE ENERGY IS ABSORVED BY THE OBJECT.
FOR EXAMPLE: IMAGINE THAT IS A SUNNY DAY AND YOU ARE INSIDE YOUR DAD´S CAR.
TRANSPARENT SUBSTANCES, LIKE GLASS OF WATER, LET LIGHT ENERGY PASS THROUGH,
BUT THEY BLOCK HEAT ENERGY. LIGHT ENERGY PASSES THROUGH THE CAR WINDOW.
WHEN THE LIGHT HITS YOU, IT IS ABSORVED. LIGHT ENERGY IS ABSORVED FOR OTHER
OBJECTS INSIDE THE CAR, SUCH AS THE RADIO O THE STEERING WHEEL.
LIGHT ENERGY IS TRANSFORMED INTO HEAT.
ALL THIS HEAT ENERGY IS BLOCKED INSIDE THE CAR BECAUSE THE GLASS DOESN´T LET IT
ESCAPE. AS A RESULT, THE TEMPERATURE INSIDE THE CAR GETS HOTTER AND HOTTER.
IF WE OPEN THE WINDOW, THE HEAT ENERGY ESCAPES AND THE TEMPERATURE GOES DOWN