P1
P1 AQA (Core Science)
INCLUDES:
Heat Transfer, Energy Transfer, Electrical Devices, Electrical Sources, Electromagnetic Radiation, Nuclear Radiation, Origins of the Universe
- Created by: self-confessed worrier :/
- Created on: 28-04-11 16:09
Heat Transfer (P1a - 1)
- to evaluate ways in which heat is transferred in and out of bodies and ways in which the rates of these transfers can be reduced
Conduction is heat flow through solids - can be stopped by trapping a layer of air around the body (involves particles)
Convection is heat flow through liquids & gases (involves particles)
All objects emit & absorb radiation
Thermal (infra-red) radiation is the transfer of energy by electromagnetic waves - all bodies emit & absorb it - the hotter a body is, the more energy is emmitted
Dark, matt surfaces are good absorbers & emitters of radiation - therefore, the lighter & more shiny a surface the worse it is at absorbing & emitting radiation
Shape and dimensions of a body affect the rate of heat transfer
(Bigger) temperature difference between an object and it's surroundings affect the rate of heat transfer
Energy Transfer (P1a - 2)
- to describe the intended energy transfers/transformations and the main energy wastages that occur with a range of devices
- to evaluate the effectiveness and cost effectiveness of methods to reduce heat loss
Efficiency = useful energy transferred by device total energy supplied to device
Energy can't be created or destroyed <-- conservation of energy
Wasted and useful energy both eventually spread out to their surroundings - which become warmer <-- the further it spreads, the harder it becomes to use again
Electrical Devices (P1a - 3)
- to compare and contrast the particular advantages and disadvantages of using different using different electrical devices
Energy transferred = power x time <-- kWh = kW x h
Total cost = number of kWh x cost per kWh
The amount of electrical energy a device transforms depends on how long the appliance is switched on for and the rate at which the device transforms energy
Energy is measured in joules
In the National Grid --> increasing voltage reduces current so reduces energy loss through friction, thereby increasing efficiency
Electrical Sources (P1a - 4)
- to compare and contrast the particular advantages and disadvantages of different sources to generate electricity
Energy from renewable sources can drive turbines directly
Using different energy resources has a different effect on the environment <-- this includes the release of substances into the atmosphere, noise & visual pollution & the destruction of habitats
Advantages & disadvantages of different energy sources depend on the cost of building power stations, start up time of power stations, reliability of energy source, the relative cost of the energy generated and the location in which the energy is needed
Electromagnetic Radiation (P1b - 5) [1]
- to evaluate the possible hazards that come with types of electromagnetic radiation
Outside the body, gamma rays are most harmful and can penetrate the skin and get to internal organs <-- although they tend to pass through cells themselves, therefore causing little harm to the cells
Alpha and beta radiation is highly ionising
- to evaluate methods to reduce exposure to different types of electromagnetic radiation
When people are around sources of radiation, full protective suits are often worn - many are often lead-lined to stop gamma rays getting through as gamma rays can kill cells
The electromagnetic spectrum is continuous but can be grouped into types of increasing wavelength & decreasing frequency
Electromagnetic Radiation (P1b - 5) [2]
The spectrum -->
Gamma, X ray, Ultraviolet, Visible Light, Infra-red, Microwaves, Radio-waves ||||||||||||| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
When radiation is absorbed, the energy it carries makes the substance, which absorbs it, hotter and may create an alternating current with the same frequency as the radiation itself
Different wavelengths of electromagnetic radiation have different effects on living cells. Some radiation mostly pass through soft tissue without being absorbed, some produce heat, some may cause cancerous and some may kill cells (effects depend on the type & dose of radiation)
Electromagnetic Radiation (P1b - 5) [3]
Radio-waves, microwaves, infra-red and visible light can be used for communication
Microwaves can pass through the Earth's atmosphere and are used to send information to satellites
Communication signals may analogue (continuously varying) or digital (discrete values only). Digital signals are less prone to interference
Electromagnetic waves obey the wave formula -->
wave speed = frequency x wavelength <-- m/s = Hz x m
Nuclear Radiation (P1b - 6)
- to evaluate the possible hazards associated with the use of the different types of nuclear radiation
(Radiation) (Use) (Hazard) (Stopped by...) (Deflected by...)
(Alpha) (Used in smoke detectors) (If taken into the body (ingested) alpha emitters harm tissue) (Stopped by paper) (Electric and magnetic fields)
(Beta) (Checking thickness of paper sheets in manufacture and radioactive tracers) (Some risk of tissue damage -->not as bad as alpha) (Stopped by aluminium) (Electric and magnetic fields)
(Gamma) (Medical research and non-destructive casting tests) (Can cause genetic damage and cancer) (Stopped by lead) (Nothing)
Some substances give out radiation from the nuclei of their atoms all of the time, whatever is done to them <-- they are radioactive
Half-life is the time it takes for the count rate to halve or the time it takes for the number of nuclei to halve
Origins of the Universe (P1b - 7)
- to compare and contrast the particular advantages and disadvantages of using different types of telescope on Earth and in space to make observations on and deductions about the Universe
If a wave source is moving relative to an observer there will be a change in the observed wavelength and frequency
There is a red-shift in light observed from the most distant galaxies
How the observed red-shift provides evidence that the Universe is expanding and supports the 'Big Bang' theory
The 'Big Bang' states that the Universe began from a very small initial point
Observations are made with telescopes that may detect visible light or other electromagnetic waves
Related discussions on The Student Room
- Test P1 »
- Electronic Configurations »
- Physics IGCSE Edexcel predictions (Paper 2) »
- IB Chemistry Paper 3 »
- Edexcel A-level Biology B Paper 2 (9BI0 02) - 16th June 2023 [Exam Chat] »
- Edexcel A Level Physics Paper 3: 9PH0 03 - 15th June 2023 [Exam Chat] »
- OCR A A-level Physics Unified Physics (H556/03) - 15th June 2023 [Exam Chat] »
- Synoptic Question - Psychology AQA GCSE »
- AQA A Level Psychology Essays »
- Edexcel IAL Maths P1 »
Comments
Report
Report
Report