IGCSE Edexcel Physics Paper 2

Describe how the student could use the rods to demonstrate that there are two different types of electric charge. (3)

• MP1 : suitable apparatus that would demonstrate rod is charged

• MP2: indication that a charged rod will apply a force on the ‘other object’

• MP3: evidence that both attraction and repulsive forces will happen with opposite and like charges

Explain how the force on the proton changes as the proton moves through the magnetic field. (2)

• force (always) at right angles (to velocity);

• causes the proton’s direction to change;

• (because) proton motion is equivalent to a current;

• (this causes) the direction of the force on the proton to change;

• idea of magnitude of force is constant;

Suggest why the velocity of the proton changes. (1)

direction changes

Give one disadvantage of generating electricity using the HEP station rather than the wind farm. (1)

• large area of land needs to be flooded; ignore visual pollution

• location dependent / mountainous area

• damage to habitats / eq;

The HEP station has an electric pump that can pump water from the lower lake back to the upper lake. The pump can be powered using electricity generated by the wind farm. Explain how the HEP station and wind farm can be used together to maximise the effectiveness of generating electricity. (3)

• idea that wind farm cannot store energy

• idea of wind powering the pump when (energy) demand is low

• idea that (therefore) upper lake acts as an energy store (for wind farm output)

• (so that) energy released from upper lake or to the HEP when demand is high

• idea that more electricity/energy is transferred usefully;

Describe two differences between evaporation and boiling. (2)

• boiling happens at a specific or fixed temperature or 100 oC but evaporation happens at any temperature

• boiling happens throughout a liquid but evaporation only happens at the surface

• at least one transformer drawn in the space between power station and school

• similar object drawn in the space between power station and school

• transformer/object nearest power station labelled “step-up” and transformer/object nearest school labelled “step-down”;

Describe how the force applied on ball A compares with the force applied on ball B during the collision. (2)

• both forces are the same size/magnitude/equal

• forces are in opposite directions;

Show that the velocity, v, of ball B after the collision is about 0.6m/s. (4)

total momentum before - momentum after on A - momentum after on B

Name one advantage of geothermal energy. (1)

• can be used all day

Give a control variable for the student’s investigation. (1)

brightness of lamp

The student states that the solar cell could be used as a power source for the lamp. They suggest that this would work if

• the solar cell is connected directly to the lamp

• the light from the lamp is used to produce the output power from the solar cell

Explain, with reference to the principle of conservation of energy, why the student’s suggestion would not work. (2)

• lamp not 100% efficient

• energy losses

Give a reason why the students do not stand nearer to the wall. (1)

• time is too short

Suggest how increasing the strength of the magnetic field will affect the proton when it is moving in the magnetic field. (2)

• idea that force increases

• acceleration increases

• proton moves in tighter circle / hits detector further to the left

Suggest a reason for the anomalous result where time is too short. (1)

• miscounted number of block hits

• timer was started late

Describe how force X and force Y change as the bag is moved towards the person’s foot. (3)

• force X decreases

• force Y increases

• total force remains same

Give two reasons why the energy from the heater is not all retained in the thermal store of the water. (2)

• heating of beaker/ thermometer

• heating of insulation

• insualtion not perfect

• hole(s) in life for thermometer

Explain whether or not the energy in the kinetic store of the particles changes when the sample is changing state. (3)

• KE stays constant

• temperature stays constant

• speed of particles does not change

• temperature is proportional to KE

The engine is designed to accelerate a spacecraft while the spacecraft is travelling through space. The spacecraft carries a mass of 0.75kg of xenon ions for the engine. When the engine is used, 9.9 × 10−8 kg of xenon ions leave the engine each second. A student suggests that this small spacecraft engine would not be useful because the acceleration it produces is very small. Evaluate the student’s suggestion. (2)

• tiny amount of fuel ‘consumed’ per second

• calculation (2)

• ‘burn’ for long time

• low acceleration for long time gives high speed change

• mass of spacecraft will be larger → smaller acceleration

Add an X to the diagram to show the position of star B when the light emitted from it shows maximum red-shift when detected on Earth. (1)

Describe the motion of the particles in the chocolate when the chocolate is at a temperature of 45°C. (2)

• movement now random

• particles are no longer in fixed position

The momentum of bird Y just before it is caught is 0.15kgm/s. Calculate the total momentum of the birds just before bird X catches bird Y. (1)

• same as momentum on bird X

Explain why a step-up transformer is used to supply the National Grid. (2)

• reduces current

• reduces heating in wire

Light from galaxy B has twice the redshift as light from galaxy A. Galaxy B is twice as far away from Earth as galaxy A. Explain how these observations support the Big Bang theory of the origin of the Universe. (2)

• twice redshift, twice speed

• larger speed, larger distance

• galaxies moving away from each other

Explain the advantage of the concrete having a high specific heat capacity when it is used to heat water in the heating system. (2)

• concrete can store a lot of energy

• water temp maintained for longer