Physics Yr 7 #1 Flashcards
Why are Metals good conductors
Bc they contain electrons that are free
Define thermal insulator
Insulators are poor conductors of heat, compared to thermals conductors. Eg wood
Define thermal conductor
Conduction
Convection
- occurs only for liquids and gas
Convection current process:
1. Heat energy at the bott9m of the pan
2. water at the bottom will get hotter. So the particles move faster. So they move apart and become less dense.
3. Thus the hot water rises, bc it’s lighter.
4. The cooler, denser water sinks and takes its place.
What is the Convection current process?
- Heat energy at the bottom of the pan
- water at the bottom will get hotter. So the particles move faster. So they move apart and become less dense.
- Therefore the hot water rises, bc it’s lighter.
- The cooler, denser water sinks and takes its place.
What are the 3 pathways of heat transfer
Conduction, convection, radiation
How do particles conduct heat
Particles transfer energy by colliding with other particles when they vibrate.
Energy transfer happens until the two surfaces are the same temperatures.
What is power
Power is the measure of how fast energy is transferred from one form to another
Definition of the waves
Peak top of a wave
Trough bottom of a wave
Frequency the number of waves passing a point each second
Amplitude the distance between the origin and the peak/trough
Wavelength the distance between one whole wave(2peaks and 2trough)
Transverse and longitutial
Transverse is the direction of the wave is a right angle to the movement of the source
Longitutial is the direction of the wave is parallel to the movement of the source
Define Vacuum
Space with no particles or air
Every hot object will emit …… (fill in the gap)
Radiation / Infrared radiation / thermal radiation / heat
Radiation travels as ……..
Waves
Can conduction and convection happen in space?
No , bc they involve particles, unlike radiation. In space there are no particles or air .
What objects give out / emit radiation?
All objects (including you)
Describe 2 factors that determine how much infrared radiation is emitted
- The type of radiation depends on their temperature.
- How much radiation they emit per second depends on the type of surface.
What do the words transmitted, absorbed and reflected mean?
Transmitted: a wave passed through or across a material (medium)
Absorbed: Energy is ‘taken-in’ by the material and the internal energy of the material will increase
Reflected:
tell me 3 things that detect infrared radiation?
- skin
- thermal imaging camera
- remote thermometer
dark colours ……. IR
light or shiny colours …… IR
absorb
reflect
what direction does radition travel in
in all directions in a straight
give 2 uses of radiation
- infrared photographs
- remote controls
- heat seeking missiles
- seaching for earthquake surviors
- chasing criminals
- making toast
- keeping homes warm
how to slow down convection. give me an example
use materials that contain pockets of air which cannot move.
eg. foam in between the walls of your house
temperature affect the rate of energy transfer. conduction, convection or radiation?
all 3!
Pinna
Pinna also known as the outer ear is the visual part of our ear. It is made from flexible cartilage covered by our skin which comes in different shapes and sizes. It’s job is to carry sound waves from the air and direct them to the ear canal
Ear drum
Y
The ear drum is like a barrier to our ears. It is very thin and delicate and is located at the back of our ear canal. When sound waves travel through the air and into the ear the eardrum will vibrate. These vibrations are essential cuz it helps travel sound further into our ear
Ossicles
The ossicles are made out of 3bones. These bones will amplify the vibrations to ensure the sound signals get stronger when they travel from the eardrum to the inner ear
Cochlea
When the amplified sound from the ossicles to the cochlea it will go through a fluid filled tunnel. Inside the tunnel thousands of tiny hair like cells will start moving. Specific hairs will move though. Like a high pitch sound some hairs will move and low pitch sounds another set of hairs will move. This creates electrical signals like messages to your brain.
