Objects become hot when the atoms in the object vibrate.
Low temperatures and high temperatures
The atoms in colder objects vibrate slower than those in hotter objects.
Bonus extra: Absolute zero ( 0 degrees Kelvin ) is the point at which molecular motion is at a minimum (try saying that 10 times fast :P)
Bigger objects generally have more heat energy i.e although a sparkler is hotter than an iceberg, since the iceberg is so much bigger it has more heat energy.
A cup of coffee will cool down because it's giving out its heat energy to the surroundings. There are 3 methods of heat transfer:
Conduction: The heat energy is passed around the object from atoms bumping into each other. Most metals are good conductors.
Convection: This type of heat transfer only occurs in fluids (gases or liquids). It is when a fluid moves around and carries heat with it. Some of the fluid gets heated and rises (because it is less dense). At the top, the fluid will cool and fall back down again. Key words: convection current
Radiation: Using this method, heat can travel through a vacuum.The energy is carried in infrared waves.
Refraction Keywords Galore
Refraction: The bending of light through different materials
Opaque: Lets no light through
Translucent: Lets some light through
Transparent: Lets all light through
Incident ray: The beam of light that is arriving in a prism
Angle of incidence: The angular distance of the incident ray from the normal
Normal: A line straight through the middle of the prism
Refracted ray: The beam of light that comes out of a prism
Angle of Refraction: The angular distance of the refracted ray from the normal.
Light + Lenses
Convex lenses make light converge
Concave lenses make light diverge
White light splits into different colours when it travels through a prism.
Remember ROY G BIV
Sound and Hearing
- Sound travels as waves formed when something vibrates
- Sound needs a medium to travel through!
- High pitched noises are high frequency
- Low pitched noises are low frequency
- Loud noises have high amplitude
- Quiet noises have low amplitude
- Frequency is measured in Hertz
- Human hearing is from around 20Hz to 20kHz.
- Amplitude is measured in decibels (dB)
- Sounds above 80dB can damage your hearing.