AQA GCSE PHYSICS UNIT 1 Question Game!

Original post by Mahrez

Explain how convection occurs in an immersion heater?

1. at the bottom water is heated by conduction
2. this gives water more kinetic energy and so more movement
2. this makes them move away from each other more creating large gaps between particles.
3. creates expansion
4. the warm water becomes less dense and rises
5. it rises above the cool dense water and displaces it
6. the cool water falls and fills in the gap created by the warm water rising
7. the cool water is heated again
8. this is called convection currents, a circulation of the fluid water.

thank you hafsa!!

(edited 7 years ago)

Reply 22

TeenPolyglot

20

Original post by madredjake

Q: Explain the role of step up and step down transformers

Step up transformers increase the voltage within the National Grid to 132,000V so less energy is lost along the cables.
The voltage is then stepped down by the step down transformers to 230V to make it safe for houses.

What is a U-Value?

Reply 23

username2312801

18

Original post by TeenPolyglot

Step up transformers increase the voltage within the National Grid to 132,000V so less energy is lost along the cables.
The voltage is then stepped down by the step down transformers to 230V to make it safe for houses.

What is a U-Value?

U-value is how effective a material is.

Explain condensation and evaporation

Reply 24

Original post by madredjake

Q: Explain the role of step up and step down transformers

Step up transformers increase the voltage up to 400,000 volts and reduces the current to a low level so that minimul heat loss occurs throughout the cables and pylons to increase efficieny as energy transfer would be kept low.
Step dwn transformers reduce the voltage down to 230V so that it can be used suitably for consumer appliances and also because it's so much safer.

BOOM

Reply 25

Original post by madredjake

Q: Explain the role of step up and step down transformers

step up increase voltage and decrease current, and step down decrease voltage and increase current, so that the least amount of energy is wasted and lost to the surroundings as heat.

Reply 26

madredjake

What is a U-Value?

U-value is the measure of how effective a material is as an insulator.

Reply 27

Original post by CaSama9

1. at the bottom water is heated by conduction
2. this gives water more kinetic energy and so more movement
2. this makes them move away from each other more creating large gaps between particles.
3. creates expansion
4. the warm water becomes less dense and rises
5. it rises above the cool dense water and displaces it
6. the cool water falls and fills in the gap created by the warm water rising
7. the cool water is heated again
8. this is called convection, a circulation of the fluid water.

its called convection CURRENTS :P

Reply 28

Original post by nisha.sri

U-value is how effective a material is.

Explain condensation and evaporation

Condensation is when a gas rich in Kinetic energy which has overcome attractive forces, loses energy and has particles which slowed down, and form forces again attracting particles closer together forming a liquid.

Evaporation is when energetic particles escape the surface of a liquid.

Explain how the surface of a mirror becomes misty in a shower.

Reply 29

Original post by nisha.sri

U-value is how effective a material is.

Explain condensation and evaporation

Evapouration is when the particles gain kinetic energy, become less dense and expand and rise. The particles have weak forces of attraction hence it is gas.
Condensation is when the gas cools at the surface, loosing it's kinetic energy.
The rate of evapouration depends on:
surface area
area flow

Rate of condensation depends on:
Density
Airflow
Temperature

Reply 30

explain the cooling effect (3 marks)

Reply 31

Original post by madredjake

What is a U-Value?

U-value is the measure of how quick energy is transfered in a material and therefore how effective an insulating material is :tongue:

What factors affect the rate of Evaporation and condensation? loads of marks

Reply 32

Original post by hafsa473

explain the cooling effect (3 marks)

The particles woith higher kinetic energy will evapourate into the atmosphere thus decreasing the overall/mean kinetic energy in the container

Reply 33

Original post by Mahrez

Evapouration is when the particles gain kinetic energy, become less dense and expand and rise. The particles have weak forces of attraction hence it is gas.
Condensation is when the gas cools at the surface, loosing it's kinetic energy.
The rate of evapouration depends on:
surface area
area flow

Rate of condensation depends on:
Density
Airflow
Temperature

Perfect but I think you're mixing this with convection, it's better to just say that energetic particles escape :smile:

Reply 34

username2312801

18

Original post by CaSama9

U-value is the measure of how quick energy is transfered in a material and therefore how effective an insulating material is :tongue:

What factors affect the rate of Evaporation and condensation? loads of marks

Evaporation - S.A,Temperature,Air flowing, Density
Condensation - S.A, Density,Air flowing

Why does a mirror get misty ?

Reply 35

Original post by Mahrez

The particles woith higher kinetic energy will evapourate into the atmosphere thus decreasing the overall/mean kinetic energy in the container

tut tut wheres the 3rd mark

Reply 36

Original post by CaSama9

Perfect but I think you're mixing this with convection, it's better to just say that energetic particles escape :smile:

but technically thats how particles escape but I might be tbh

Reply 37

madredjake

Explain how a hydroelectric plant is used to generate electricity

Reply 38