Physics Unit 1

Dark, matt = GOOD radiation emitter, GOOD radiation aborber

Light, shiny = POOR radiation emitter, POOR radiation absorber, GOOD reflector of INRARED RADIATION

THE HIGHER THE TEMPERATURE = THE MORE ENERGY EMITTED AS INFRARED RADIATION

KENETIC THEORY = OBJECTS ARE MADE UP OF PARTICLES THAT ARE CONSTANTLY MOVING

SOLIDS: Particles VIBRATE about fixed positions. Solids have fixed shape.    Add energy

 LIQUIDS: Partiles move around, stay close together. Liquids can flow.    

The amount of energy a particle has is related to temperature of material

    

 

CONDUCTION =

• Particles in solid given more energy and vibrate more.
• Collide with neighbouring particles, then they vibrate more

Energy spreads through solid. 

CONVECTION=

• Particles in liquid or gas given more energy, move faster and spread out.
• Density is lower so hot material rises
• Replaced by cool material, so convection current is set up

Evaporation takes place faster when:

• Temperature is higher
• Large surface area in contact with air
• Wind blows water vapour away

• Flask is made of INSULATING MATERIAL, slows energy transfer from hot liquid to outside by CONDUCTION.
• Vacuum between two layers, so energy cannot be transferred by CONVECTION.
• Silver coating reduces amount of enery transfer by RADIATION.

STEP-UP TRANSFORMERS = INCREASES voltage, DECREASES current

ADVANTAGES

• Pylons are form of visible pollution.
• People can be injured if climbing pylons, less likely to be injured by buried cables

DISADVANTAGES

• Burying cables is more expensive
• More difficult to make repairs
• Digging trenches damages habitats temporarily