Corrections

Question 1

When investigating affects of light on an LDR with a lamp where must the experiment be conducted and why

Answer 1

• in a darkened room
• so no ambient light affects the LDR

Question 2

How can you measure the volume of an irregular shape lighter than water (3)

Answer 2

• submerge it with a sinker
• measure the total volume displaced by object and submerging object
• subtract the volume displaced by sinker alone

Question 3

explain in terms of particles why solids have greater densities than water

Answer 3

• more closely packed particles
• more mass per unit volume

Question 4

voltage of sockets in a ring main

Answer 4

230 V

Question 5

advantages of a ring main (5)

Answer 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

Question 6

In the change of state from solid to liquid what does breaking of bonds allow particles to do

Answer 6

slide past one another

Question 7

In the change of state from liquid to gas what does the breaking of bonds allow particle to do

Answer 7

allows them to escape from one another

Question 8

purpose of the iron core in a transformer (2)

Answer 8

• links the alternating magnetic field from the primary to secondary coil
• strengthens the magnetic field

Question 9

what type of line of best fit is drawn on a current - voltage graph for a resistor

Answer 9

straight line

Question 10

Describe a test to test if a component is a diode (3)

Answer 10

• 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)

Question 11

Why does a satellite in geostationary orbit above the equator appear to stay in a fixed place above the Earth (2)

Answer 11

• satellite orbits in the same time
• that it takes the Earth to spin once

Question 12

what is the Earth wire

Answer 12

takes current away from an appliance when a fault occurs for protection

Question 13

explain in terms of particles how heat conducts through copper (4)

Answer 13

• 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

Question 14

explain why the liquid in the heated solar panel circulates (4)

Answer 14

• heated liquid is less dense
• heated liquid rises
• colder liquid falls
• convection current form

Question 15

how does a generator make electricity in a power plant (3)

Answer 15

• fuel is burned to heat water
• kinetic energy of steam turns a turbine
• turbine turns generator producing electricity

Question 16

how would you work out if power is proportional to screen size in TV’s

Answer 16

• 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

Question 17

why should consumers be encouraged to choose appliances that use less energy (2)

Answer 17

• so less fossil fuels are burnt
• reducing impact on global warming

Question 18

what do you use to measure mass

Answer 18

a balance

Question 19

how can you measure the volume of an irregular object (3)

Answer 19

• 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

Question 20

what is a transverse wave

Answer 20

the vibrations are perpendicular to the direction of wave travel

Question 21

what is a longitudinal wave

Answer 21

the vibrations are parallel to the direction of wave travel

Question 22

Describe the function of the Earth wire (2)

Answer 22

• carries current safely to the ground to prevent electrocution
• if the metal of an appliance frame becomes live

Question 23

state two differences between ac and dc current

Answer 23

• ac is a current that continuously changes direction
• ac is a current that continuously changes in magnitude

Question 24

why does water move in convection currents when heated (2)

Answer 24

-heated water’s volume increases and its density decreases
-cooling water’s volume decreases audits density increases

Question 25

in detail explain the process of conduction in COPPER in terms of motion of particles (6 marker)

Answer 25

- 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

Question 26

Reasons why the use of nuclear power stations have not changed over years (3)

Answer 26

- they do not produce CO2 emissions - nuclear power stations run all the time - no new nuclear stations have come on line

Question 27

Percentage decrease =

Answer 27

Decrease/original amount x 100

Question 28

Comment on the progress being made in achieving the government’s overall target for CO2 emissions by 2027 (2)

Answer 28

- Good progress is being made in the electricity generation sector - however there are other sources of emission that haven’t been taken into consideration

Question 29

what word describes the metal casing of an alliance that is in contact with the live wire

Answer 29

live

Question 30

explain why an aluminium window loses heat at a faster rate than uPVC window (aluminium has a metal spacer, uPVC - a nonmetal spacer) (4)

Answer 30

- 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

Question 31

explain how heat is lost through the roof of a house (3)

Answer 31

- 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

Question 32

why does reducing energy loss from homes benefit the environment (3)

Answer 32

- 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

Question 33

FULLY describe the National Grid

Answer 33

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.