Paper 2 Questions

Question 1

A student measures the density of glass. The student has:
- a bag of marbles, all from the same type of glass
- a weighing scale
- a plastic measuring cylinder containing water.
Describe how the student could find, as accurately as possible, the denisty of the marbles [4]

Answer 1

An investigation to find the density of the marbles would be:

Method

Find the mass of the marbles; [1 mark]
Put the marbles into the water and measure the change in volume / water level; [1 mark]
Divide the mass by the volume OR use the equation rho space equals space m over v; [1 mark]
To improve accuracy

Any one from:

Use as many marbles as possible / 5-10 marbles to improve accuracy; [1 mark]
Subtract mass of bag from mass of marbles plus bag; [1 mark]
View water level at eye level; [1 mark]
Use appropriate size of measuring cylinder; [1 mark]

Question 2

When the gas in the container is heated, the piston covering it moves upwards.
Describe what happens to the gas particles [3]

Answer 2

• The mass of the particles remains the same; [1 mark]
• The gas particles move faster; [1 mark]
• The average distance between the gas particles increases; [1 mark]

Question 3

When a bicycle pump is used to inflate the tube, the air in the bicycle pump gets warm. You should ignore any effects of friction in the pump. Explain why the air in the bicycle pump gets warm. [2]

Answer 3

• work is done (in compressing the air) [1]
• increases the kinetic energy of the (air) particles / thermal energy (of the system) [1]

Question 4

The resistor becomes warm when there is a current running through it. Explain why the resistor gets warm [2]

Answer 4

• There are collisions between (moving) electrons and the lattice (of the metal wire in the resistor); [1 mark]
• (Which makes the) lattice vibrate more OR the kinetic energy of the lattice increases; [1 mark]

Question 5

Explain why the resistance of the filament changes as the voltage across it increases [3]

Answer 5

Any three from:
- The resistance increases; [1 mark]
- Due to heating of the filament; [1 mark]
- Because there are more collisions; [1 mark]
- Of electrons with the metal ions; [1 mark]

Question 6

Explain how lightning is formed between clouds and the earth [3]

Answer 6

Any three from:

• The ground is charged (by induction); [1 mark]
• The charge on ground is positive; [1 mark]
• An electric field builds up (between cloud and ground); [1 mark]
• The air is ionised; [1 mark]
• Electrons travel to the ground OR positive ions travel to the cloud; [1 mark]

Question 7

Describe the cause of a changing magnetic field in a transformer [2]

Answer 7

• An alternating /changing current; [1 mark]
• In the primary coil; [1 mark]

Question 8

Some forces act at a distance
One example is the gravitational attraction between the Moon and the Earth. Describe an example of another type of force acting at a distance, where the force is not gravitational

Answer 8

• magnetic [1]
• force between two poles [1]

Question 9

State what is meant by the moment of the force [1]

Answer 9

Turning effect [1]

Question 10

Describe the cause of the changing magnetic field in the core of the transformer. [2]

Answer 10

• an alternating /changing current (1)
• in the primary coil (1)

Question 11

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A teacher is demonstrating electromagnetic induction.
The teacher has a bar magnet, a coil of wire and a sensitive voltmeter.
Explain how the teacher could use this apparatus to demonstrate the factors affecting the size and direction of the induced potential difference. [4]

Answer 11

• move magnet towards coil and then away from coil (1)
• with note change in ‘direction’ of meter (1)
• move magnet quickly then slowly (1)
• with larger / smaller meter reading (1)

Question 12

Explain why the resistance of the filament lamp changes as the voltage across it increases.

Answer 12

• identification of resistance increasing (1)
• heating (of the filament) (1)
• because of more collisions (1)
• of electrons (with ions / atoms /other electrons) (1)

Question 13

Describe what happens when a substance experiences sublimation. [2]

Answer 13

• dea of change of state / solid changes (1)
• to gas / vapour (directly) (1)

Question 14

Pumping fuel into an aircraft can be dangerous.
The worker connects an earth wire to the aircraft before pumping fuel.
Give one reason why earthing reduces the risk of fire. [1]

Answer 14

The earth wire discharges the aircraft to prevent sparking
which could ignite the fuel/cause a fire