Infra Red Radiation
Any warm or hot objects send out some waves of infra red radiation, which carry heat. IR Radiaton can travel through everything
- A hot dull surface gives out more IRR than a hot shiny surface.
- When IRR goes towards a shiny surface, the heat reflects however IRR gets absorbed by a dark and dull surface.
Heat can also be transferred from one object to another, or from one molecule to another through the process of conduction.
As one molecule is heated it begins to move and shake rapidly.
As it does so, it passes some of its heat energy to other molecules around it.
Through this process, all the molecules of an object pass heat from one to another, until they are all hot.
Convection takes place when heated molecules move from one place to another, taking the heat with them.
Heated air in our atmosphere expands, becoming less dense.
Because it is less dense, it rises upward.
Cooler air rushes in to replace the air that lifted up.
As warm air rises, and cool are falls, a giant circular pattern is created.
Eventually the warmer air cools, and begins to fall again.
Summary of Electricity
- A flow of current is the movement of electrical charge, usually electrons
- Current flow is from the positive to negative terminal ( left to right)
- A group of cells are called batteries
- In a series curcuit, the current flows round a continous loop
- In a parrarel circuit, the current splits of into seperate branches.
- An ammeter measures current in amps
- A voltmeter measures PD (potential difference) in volts.
Light, Reflection and Refraction Summary
- A lumious object gives of its own light
- light travels in straight lines
- Light is reflected off objects and into our eyes
- Opaque objects blocks light to cast shadows.
- Light is reflected from a surface
- The angle of incidence is the same as the angle of reflection
- The image in a mirror is back to front (laterally inverted)
- A periscope will reflect light and let you see around corners.
- The bending of light is called refraction
- Total Internal Reflection occurs when the angle of incidence reaches the critical angle.
- Vibrating molecules carry sound energy
- There needs to be air for sound to be heard.
- The higher amplitude of sound, the louder it is.
- Pitch depends on frquency. High frequence gives a high pitch.
- Sound travels at 330ms
The Solar System
Day and Night
The earth spins on its axis to give us day and night. The earth spins 24hrs to make a complete revolution.
Only places on the equator get 12 hours of equal day light
We have seasons because the earth is tilted as it makes its yearly orbit around the sun.
The tilt of the Earth means the Earth will lean towards the Sun (Summer) or lean away from the Sun (Winter) 6 months later.
In between these, Spring and Autumn will occur.
The Earth's axis is tilted at an angle of 23.5 degrees.
Movement of Planets in the solar system
9 Planets orbits the sun.
They all rotate at the same time to give day and night
The Moon orbits around the planet.