1. P4 6 mark question practice

4. Electricity can be dangerous, if a fault occurs in a circuit a shock could be fatal. Describe two safety measures used in the UK to reduce the risk of a fatal accident. Describe what a fuse does Describe what an Earth wire does Explain how each increases safety

5. Electricity can be dangerous, if a fault occurs in a circuit a shock could be fatal. Describe two safety measures used in the UK to reduce the risk of a fatal accident. A fuse is connected to the live wire A fuse will melt if there is a fault causing too much current to flow This causes the fuse to heat up and melt/break This breaks the circuit and stops the current flowing The fuse protects the user from shocks, fires and ‘blown’ appliances If a fault occurs that causes the live wire to touch the edge of an appliance the user could get a shock The Earth wire is connected to the edge of an appliance If there is a fault the current will flow through the Earth wire to the ground This prevents a current flowing through the user if they touch the faulty device

6. Static electricity can be very useful when used correctly. Explain how an object can become charged and describe one use of static electricity. Describe the role of electrons Explain how static electricity is used in: –Paint spraying –OR –Smoke Precipitators –OR –Defibrillators

7. Static electricity can be very useful when used correctly. Explain how an object can become charged and describe one use of static electricity. When two insulators are rubbed together they can become charged through friction Electrons move from one material to another If an object gains electrons it becomes negatively charged, if it loses electrons it becomes positively charged

8. spray gun charged paint particles charged the same so repel giving a fine spray and coat object charged oppositely to paint so attracts paint into the ‘shadows’ of the object giving an even coat with less waste. High voltage metal grids put into chimneys to produce a charge on the dust Dust particles gain or lose electrons Dust particles induce a charge on the earthed metal plate dust particles are attracted to the plates. paddles charged good electrical contact with patient’s chest charge passed through patient to make heart contract care taken not to shock operator.

9. Explain how measurements from radioactive carbon can be used to find the date of old materials. What is radioactive carbon What happens to the amount of it when a living thing dies

10. Explain how measurements from radioactive carbon can be used to find the date of old materials. Cosmic rays from the sun interact with the carbon dioxide in the atmosphere to make Carbon-14 Carbon-14 is a radioactive isotope that is unstable The unstable Carbon-14 will decay with a half life of 5700 years The amount of Carbon-14 in the air has not changed for thousands of years When an object dies (e.g. wood) gaseous exchange with the air stops, it no longer takes in carbon dioxide As the Carbon-14 in the wood decays the activity of the sample decreases The ratio of current activity from living matter to the activity of the sample is used to calculate the age within known limits.

11. A nuclear power station uses a fission reaction to release energy. Describe a nuclear fission reaction and explain how the reaction is controlled in a power station It starts with a neutron Remember to state that energy is released Describe a chain reaction Describe the control rods

12. A nuclear power station uses a fission reaction to release energy. Describe a nuclear fission reaction and explain how the reaction is controlled in a power station Uranium nucleus hit by neutron Causes nucleus to split Energy released 2 more neutrons released. When each uranium nucleus splits more than one neutron is given out These neutrons can cause further uranium nuclei to split. Scientists stop nuclear reactions going out of control: –rods placed in the reactor to absorb some of the neutrons –allowing enough neutrons to remain to keep the process operating.