Physics - Core Flashcards
Why are metals good conductors?
They have free electrons which pass the current on by vibrating against other free electrons and ions/atoms they collide more often making the current go through quicker
What is conduction?
The process of vibrating particles passing on their kinetic energy to neighbouring particles
Name the three ways in which heat energy can be transferred
Radiation, conduction and convection
Explain the green house effect
Th sun produces short wavelengths that can pass through the atmosphere and heat objects, but the heated objects produce long wavelengths that cannot escape the atmosphere heating the earth up
What is the u-value?
The rate at which heat can transfer through a material
What is specific heat capacity?
Show us how much energy a substance can store
What are the factors that increase the rate that a object can be heated up?
- the temperature difference
- the material that it is in contact with
- shape
- surface area
How does a vacuum flask keep insulated?
Double walled - prevents conduction convection
Silver walls - prevent heat loss be radiation
Insulating foam - conduction
Stopper - reduces heat transfer
What is convection?
The movement of particles in a fluid
What happens in a convection current?
The particles in the hotter region have more energy and move faster so therefore diffuse and become less dense, they rise above the cooler ones which have little energy and are sinking they then get heated again, this is a convection current
Explain the kinetic theory
Solids - strong attraction forces which keeps them in regular arrangement little energy so vibrate in fixed positions
Liquid- weaker attraction forces but still close together, have some energy that lets them move in random directions and pass each other at slow speeds
Gas - no attraction forces, lots of energy so pass each other at high speeds in random directions
Explain the process on condensation
Gas cools so Particles loose energy Get denser and come together as there no longer able to overcome the attraction forces and then becomes a liquid
Explain the process of evaporation
The particles have enough energy and are going fast enough to leave the liquid but they must be going in the right direction
They leave the liquid lowering the average kinetic energy and temperature so the liquid cools
List types of energy that cannot be stored 6
Kinetic Light Sound Thermal Electrical Nuclear
Name the three types of energy that can be stored
Chemical
Elastic potential
Gravitational potential
What is the conservation of energy principle?
Energy can be stored, dissipated or change from one form to another, but never can it be created or destroyed
What is useful energy
Energy that is where we want it in the form that it is wanted
What happens to wasted energy?
It dissipates into the surroundings
Why can no machine be more than 100% efficient?
Because you cant get more out than what you put in
Name the 4 non renewable sources of energy
Oil
Natural gas
Coal
Nuclear fuel
Name the 8 renewable sources of energy
Food Wind Solar Wave Hydroelectric Geothermic Biofuels Tide
What does a step up transformer do?
Increases voltage and lowers current
What does a step down transformer do
Decreases voltage and increases current
What happens to the carbon in carbon capture and storage?
Goes to gas fields and oil fields
