P4 unit: Radiation for life
- Created by: Jen3005
- Created on: 20-05-16 19:12
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- P4 unit: Radiation for life
- Electrostatic charges
- When you rub two insulating materials together, a charge builds up.
- Electrons, which have a negative charge are transferred from one material to the next
- Opposite charges attract. Like charges repel.
- Electrons, which have a negative charge are transferred from one material to the next
- Opposite charges attract. Like charges repel.
- Dangers
- Sparks jumping
- Shocks
- Anti-static lines prevent the build up of charge by reducing friction
- Defibrilators use two charged paddles
- Electrostatic precipitators
- Remove smoke particles from waste gases coming from chimneys
- 1) Charged wire grid.
- Soot or dust travels through it and also becomes charged.
- 2) Two metal plates
- Charged oppositely to that of the grid
- 3)Dust sticks to the plates
- 4) Plates hit to remove the dust
- 2) Two metal plates
- High voltage
- Soot or dust travels through it and also becomes charged.
- When you rub two insulating materials together, a charge builds up.
- Voltage
- Measure of energy difference
- Measured in volts
- Measured using a voltmeter
- Current
- Measured in amps
- AC and DC
- Charge creates a current
- How powerfully electrons flow through an item
- To increase the current you can reduce resistance or increase the voltage
- Resistance
- Measured in ohms
- Current flows through the path of the least resistance
- How much an item can slow the flow of electrons
- Electrical safety
- Blue wire = neutral wire
- Completes the circuit
- Has a voltage of 0V
- Brown wire = live wire
- Provides energy to the device
- Green and yellow = earth wire
- Provides a route to eath
- Blue wire = neutral wire
- Ultrasound
- Sonar = reflection of sound
- Body scans
- Travel through the body to produce images
- Non-invasive
- Check baby development
- Reflect from layers of the body and return at different times, depending on the depth of each layer
- Kidney stones
- Vibrate kidney stones inside the body
- Stones break into small pieces
- Small enough to pass out of the body
- Stones break into small pieces
- Vibrate kidney stones inside the body
- Radiation types
- Alpha
- Positively charged
- Move at slow speeds
- Low penetrating power
- Very ionising
- Large
- Large mass
- Alpha particles have 2 neutrons and 2 protons
- Gamma
- Weak ionising power
- No mass
- Highly penetrating
- No charge
- Very fast speeds
- Beta
- Moderately penetrating
- Move at fast speeds
- Negatively charged
- Moderately ionising
- Small
- Small mass
- Alpha
- Half life
- Time taken for half of a radioactive sample to decay or for its radioactivity to halve
- Radioisotopes
- Tracers
- Radioactive substances that accumulate in a certain area
- Use gamma radiation
- They are very penetrating
- Can detect leaks
- Radiation accumulates where the leak is
- Medical
- Diagnostic
- Can scan for tumours
- Radiotherapy
- Treats cancer
- Works to minimise damage to healthy cells
- Gamma rays scan a set target and rotate around it.
- This keeps the radiation focused on cells that need to be killed, not the healthy ones.
- Sterilising equipment
- Diagnostic
- Tracers
- Carbon dating
- When an organism dies, gaseous exchange stops
- activity of the sample : the activity in living matter calculates the age.
- The amount of carbon-14 in the atmosphere has remained the same for thousands of years
- Uranium dating
- Uranium decays to lead
- Comparing the ratio of uranium to lead atoms in a sample, its age can be estimated
- Nuclear fission
- In order to generate heat, an atom of uranium splits
- A neutron is fired at an atom so it changes shape and splits
- In order to generate heat, an atom of uranium splits
- Neutrons released from split atoms hit other atom, causing a chain reaction
- Rods are put into the reactor to stop the reaction spreading too far
- Rods can be pulled up or down to control how many atoms split.
- Nuclear fusion
- In stars, the nuclei moves very fast to get close enough to other nuclei to fuse.
- This is achieved because of the intense pressure and heat. They are moving so fast they smash together
- Joining two nuclei together
- The conditions necessary to create nuclear fusion is too intense to be safely reproduced and maintained on earth
- Fleischman and Pons claimed to have achieved cold fusion and could fuse atoms together at room temperature
- Nobody has since been able to repeat it so these claims are seen as false
- In stars, the nuclei moves very fast to get close enough to other nuclei to fuse.
- Beta decay
- The numbers on the top of the symbols must be the same.
- On the bottom of the symbols,he first two numbers must equal the last one
- Alpha decay
- There must be two protons and two neutrons
- When the nucleus emits an alpha particle, it loses 2 protons and 2 neutrons
- Electrostatic charges
- Beta
- Moderately penetrating
- Move at fast speeds
- Negatively charged
- Moderately ionising
- Small
- Small mass
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