Corrections Flashcards
When investigating affects of light on an LDR with a lamp where must the experiment be conducted and why
- in a darkened room
- so no ambient light affects the LDR
How can you measure the volume of an irregular shape lighter than water (3)
- submerge it with a sinker
- measure the total volume displaced by object and submerging object
- subtract the volume displaced by sinker alone
explain in terms of particles why solids have greater densities than water
- more closely packed particles
- more mass per unit volume
voltage of sockets in a ring main
230 V
advantages of a ring main (5)
- cables can be made thinner
- each part of the cable carries less current
- sockets can be placed anywhere
- each socket has 230V applied
- sockets can be operated separately
In the change of state from solid to liquid what does breaking of bonds allow particles to do
slide past one another
In the change of state from liquid to gas what does the breaking of bonds allow particle to do
allows them to escape from one another
purpose of the iron core in a transformer (2)
- links the alternating magnetic field from the primary to secondary coil
- strengthens the magnetic field
what type of line of best fit is drawn on a current - voltage graph for a resistor
straight line
Describe a test to test if a component is a diode (3)
- connect in series one way and see if the current is high
- reverse the cell
- see if the current is zero (a diode only lets current flow one way)
Why does a satellite in geostationary orbit above the equator appear to stay in a fixed place above the Earth (2)
- satellite orbits in the same time
- that it takes the Earth to spin once
what is the Earth wire
takes current away from an appliance when a fault occurs for protection
explain in terms of particles how heat conducts through copper (4)
- the particles vibrate faster
- they collide with neighbours, transferring heat energy
- copper also has free electrons that move faster
- electrons pass on the energy as they move through the lattice
explain why the liquid in the heated solar panel circulates (4)
- heated liquid is less dense
- heated liquid rises
- colder liquid falls
- convection current form
how does a generator make electricity in a power plant (3)
- fuel is burned to heat water
- kinetic energy of steam turns a turbine
- turbine turns generator producing electricity
how would you work out if power is proportional to screen size in TV’s
- compare ratio of screen size to power of the 2 TV’s
- ( TV 1’s screen size divided by power = … and
- TV 2’s screen size divided by power = …)
- if the two numbers are the same then the ratio is the same so its true
why should consumers be encouraged to choose appliances that use less energy (2)
- so less fossil fuels are burnt
- reducing impact on global warming
what do you use to measure mass
a balance
how can you measure the volume of an irregular object (3)
- fill a measuring cylinder with water (ensuring there is space left for the pebble). Record the volume in cm3
- carefully place the pebble into the measuring cylinder and determine the new volume
- subtract the volume of water from the volume of the water +the pebble
what is a transverse wave
the vibrations are perpendicular to the direction of wave travel
what is a longitudinal wave
the vibrations are parallel to the direction of wave travel
Describe the function of the Earth wire (2)
- carries current safely to the ground to prevent electrocution
- if the metal of an appliance frame becomes live
state two differences between ac and dc current
- ac is a current that continuously changes direction
- ac is a current that continuously changes in magnitude
why does water move in convection currents when heated (2)
-heated water’s volume increases and its density decreases
-cooling water’s volume decreases audits density increases
in detail explain the process of conduction in COPPER in terms of motion of particles (6 marker)
- the molecules at the ‘high temperature end’ of the substance gain energy
- and vibrate with increasing kinetic energy
- they transfer their energy to neighbouring molecules by collisions and this continues through the body of the material
- copper has free electrons which gain energy at the ‘high temperature end’
- and move towards the ‘lower temperature end’
- transferring energy more quickly
Reasons why the use of nuclear power stations have not changed over years (3)
- they do not produce CO2 emissions
- nuclear power stations run all the time
- no new nuclear stations have come on line
Percentage decrease =
Decrease/original amount x 100
Comment on the progress being made in achieving the government’s overall target for CO2 emissions by 2027 (2)
- Good progress is being made in the electricity generation sector
- however there are other sources of emission that haven’t been taken into consideration
what word describes the metal casing of an alliance that is in contact with the live wire
live
explain why an aluminium window loses heat at a faster rate than uPVC window (aluminium has a metal spacer, uPVC - a nonmetal spacer) (4)
- aluminium is a better conductor
- metal spacer conducts heat from the inner pane to the outer pane
- increased vibrations pass on energy from one particle to another
- free electrons transfer energy from a high to low temperature
explain how heat is lost through the roof of a house (3)
- heat conducts through the ceiling to the loft
- as air is heated it becomes less dense and rises
- creating a convection Curren† in the loft space
why does reducing energy loss from homes benefit the environment (3)
- heating is used to replace energy lost
- if you lose less heat your heating doesn’t need to be on for as long
- less fossil fuels are burned
FULLY describe the National Grid
A network of power stations, transformers and power lines all joined together, supplying electricity to consumers. They monitor and respond to changes in supply and demand.
