Physics exam questions P4

Joe is wearing rubber-soled shoes. He walks across some carpet. When he touches a metal tap he feels a shock. Explain why

- charge transferred to him from carpet
- metal tap is am conductor
- negatively charged electrons passed from joe to tap and down to earth

When a fuel is being pumped into an aircraft there is a risk of explosion. Explain why

- friction between fuel and nozzl�
- build up of friction could cause plane to be charged
- lead to spark
- spark ignite fuel vapour

Explain how ultrasound is used to observe an unborn foetus

- ultrasound waves transmitted into body
- waves partially reflected at boundary between different materials on body
- time taken for reflected wave to be detected used to calculate depth of boundary
- image produce on screen

The isotope is not poisonous and has suitable half life. What other information do we need to know before deciding if it is suitable for use as a tracer?

- type of radiation emitted
- how penetrating it is
- how ionising it is

Kettle 1 is correctly wired,kettle 2 is not. If there is a fault explain how fuse and earth wire protects the person using kettle 1 but not the person using kettle 2

KETTLE 1 SAFE: live wire touch metal case then large currrent to earth
- fuse melt so kettle not live
- current stops
KETTLE 2 NOT SAFE: live wire touches metal case
- fuse does not melt so kettle live
- current does not stop
MISTAKE IN WIRING OF KETTLE 2

Explain how a pipe with a wire mesh in it can prevent sparks when filling a car

- wire mesh made of metal= good conductor
- charge is removed

Describe nuclear fusion and explain why not yet a possible energy resource on earth

- nuclear fusion is process by which heat energy is released when nuclei fuse together e.g in stars and fusion bombs
- large amount of heat energy is released
- can only happen at extremely high temperatures
- difficult to maintain high temperatures there

Suggest two uses of electrostatics

- spray painting
- smoke precipitators
- defibrillators

What happens during beta emission?

- atom decays by changing a neutron into a proton and electron
NEW ATOM:
- atomic number increased by 1
- mass number stays same

What happens during alpha emission?

- atom decays by ejecting an alpha particle ( helium nucleus 2 protons and 2 neutrons)
- NEW ATOM:
- atomic number decreased by 2
- mass number decreased by 4

What are the three wires in a three pin plug?

- EARTH: green and yellow
- LIVE - brown
-NEUTRAL - blue

' double insulated appliances require neither a fuse or an earth wire' is this true or false?

FALSE.
Because they still require a fuse to protect the appliance

Many appliances have a metal casing. Describe how the earth wire and fuse work together to protect the user if a fault occurs

- casing becomes live
- short circuit
- current flow through earth wire - less resistance so current increases
- fuse melts
- circuit broken

Explain how a radioactive tracer can be used to check for a blockage in a pipe

- radioactive material put in pipe
- detector tracks progress of radioactive material
- reduction in radioactivity after a certain point indicates blockage

Explain the purpose of the alpha emitter in the smoke detector

- alpha particles ionises air
- electric current flows between electrodes
- smoke absorbs alpha particles
- no ionisation and reduced or no current
- alarm sounds

Explain how carbon dating is used to age ancient artefacts

- once living organism ingest carbon 14
- whilst organism alive amount of carbon 14 decreases
- compare remaining amount of carbon 14 to similar living organism

Explain why gamma rays can be used to treat cancer and describe some of the potential risks and benefits of this treatment

- radiotherapy gamma rays of specific dosage are focused on tumour
- gamma rays as ionising kill the cells that make up tumour
- leads to shrinkage or disappearance of tumour
RISKS: - damage living tissue around tumour lead to future health problems
- ris

Describe the main stages of electricity production

- nuclear fuel - atoms split/release heat energy
- heat used to turn water into steam
- steam turns turbine
- turbine turns generator
- produces electricity

One group of scientists claims to have successfully carried out a cold fusion experiment. Explain why it is important that the experimental method and any data for this experiment is shared amongst the scientific community

- if could cold fusion could be carried out could revolutionise energy production
- other scientist must be able to use same methods to produce similar results
- data and method may help other scientists develop other areas of research

Explain how a chain reaction continues onces started

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How do control rods stop the chain reaction getting out of control?

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