P1 - Exam Mistakes Flashcards
Why does decreasing the temperature of a thermostat by 1 degree not always save the same amount of energy? 2 marks
Heating is on for more / less time than anticipated
Because some days it is cooler or warmer
What is meant by the term U-value?
How effective a material is as an insulator
As the amount of insulation increases, the U-value decreases
Give 5 properties of all electromagnetic waves
Transverse
Same speed
Can be reflected, refracted and diffracted
What type of electromagnetic wave provides the most heat?
Infrared
What effect does the Doppler effect have on wave speed?
No effect (same speed)
Describe how conduction happens through a metal
There are free electrons in a metal
They gain kinetic energy
Transfer energy to other electrons, ions and atoms
By collision
How is a convection current set up?
Particles spread out
Which causes the air to become less dense
So the warm air rises
Why would you make a surface light and shiny?
Surface is good reflector if IR radiation
To stop radiation being absorbed
What changes so you make to a sound wave to make it louder or higher in pitch?
The shorter the wavelength (more waves seen in a given length), the higher the pitch
The larger the amplitude, the louder the sound
What do you have to say in convection questions?
Cool air gives more densely packed particles (particles closer together)
What effect does the waste energy from a power station have on its surroundings?
It warms it (because the waste is heat)
What is the national grid?
A system of cables and transformers
What is a virtual image?
An image that can’t be formed on a screen
What is the importance of the short start up time of hydroelectric power stations?
To meet surges in electricity demand
Give 3 reasons that the amount of electricity used in homes would decrease nationally
Energy efficient appliances
Increased energy cost causing people to turn off appliances more
More people becoming environmentally aware
What is the wavelength range of the electromagnetic spectrum?
10^-15 metres to 10^4 metres
Describe how filling an air gap with plastic foam will reduce energy transfer by convection
Air trapped in the foam
So the air can’t circulate and form a convection current
How does increasing the number of cooling fins affects the rate of energy transfer from a radiator?
Fins increase surface area
Increases rate of energy transfer
What 2 pieces of information can be found about a galaxy when the size of the red shift the galaxy produces is measured?
Distance from Earth
Speed galaxy is moving
What is meant by decommissioning a nuclear power station?
Dismantle and remove radioactive waste
Explain the effect of replacing a wall with glass doors on the rate of energy transfer from the house. 2 marks
Rate of energy transfer is greater
Because glass isn’t as good an insulator as wall
Why would a radiator be painted black? 2 marks
Black surfaces is better emitter of infrared radiation
Increases rate of heat transfer
Give an ethical implication of increasing energy production in developed countries
Damage to global environment affects all
What direction are most galaxies travelling in?
They are moving away from EACH OTHER
What is a reliable way of generating electricity?
Can generate the same amount of energy all of the time
Explain why voltage in National Grid cables is high. 3 marks
To lower current
To reduce loss of energy by heat from cables
So increases efficiency of transmission
One kilogram of a gas has a larger volume than one kilogram of a solid. Use kinetic theory to explain why. 4 marks
Strong forces of attraction between particles in a solid
Holding the particles close together
The forces between gas particles are very small
So the particles spread out to fill their container
What would show a higher pitch on an oscilloscope?
More waves seen (NOT WAVELENGTH OR FREQUENCY)
