Mapa mental
Physics 1
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Physics 1
Heat is a measure of energy (measured in Joules).
Heat is measured on an absolute scale.
There is no such thing as cold energy, if something is cold it is because it doesn’t have much heat energy.
Temperature is a measure of hotness (measured in °C)
The hotter something is in comparison to its surroundings, the quicker it will cool down.
A thermogram indicates temperature.
Heat energy always flows from hotter to cooler bodies.
Specific Heat Capacity (c) is the energy needed to raise the temperature of a 1kg block of a material by 1°C.
A high specific heat capacity will mean the material takes a lot of energy to heat up, and has to lose a lot of energy to cool down
Specific Latent Heat is the energy needed to change the state of 1kg of a material.
When a material changes state, the temperature does not increase as the energy is used to break intermolecular bonds rather than increasing the kinetic energy of the molecules.
A high specific latent heat means it takes a lot of energy to change its state (i.e melt or evaporate).
The particles in a hot object have more kinetic energy than a cold object.
Heat is transferred by conduction by the particles vibrating and making those next to them vibrate.
Conduction only occurs in solids as the particles cannot move around.
Warm air is less dense and so rises.
Convection is the movement of air from one place to another.
Heat is transferred by radiation as a wave.
Radiation can occur in all states of matter and a vacuum as it doesn’t need particles.
Trapped air is a good insulator as the particles aren’t close enough together for conduction to take place and the particles can’t move so convection can’t take place.
A cavity wall is 2 layers of bricks with a gap inbetween.
Some cavity walls have foam in the gap, this is called cavity wall insulation.
Electromagnetic waves travel in straight lines
EM Spectrum in order of wavelength: Gamma X-Ray UV Light Infrared Microwaves Radiowaves
If wavelength increases then frequency decreases.
Reflection is when a wave changes direction by bouncing off an surface
Refraction is when a wave changes direction by entering a different material.
Refraction occurs because waves go at different speeds in different materials.
Diffraction is when waves spread out after going through a gap.
Diffraction occurs the most when the gap is a similar size to the wavelength.
Using light increases the speed of communication
Total internal reflection is when a wave stays inside a material by bouncing off the internal walls.
Total Internal Reflection occurs when the angle of incidence is bigger than the critical angle for the materials.
If the angle of incidence is too small the light will leave the material rather than staying inside.
Lasers produce an intense, narrow beam of light of a single colour (monochromatic).
The waves in a laser beam are coherent, which means they are all in phase.
Lasers can be used in surgery and dental treatment, for cutting materials in industry, weapon guidance and in laser light shows.
Morse code is a series of on off signals, which means it is digital.
The best emitters and absorbers are dull and black.
The worst emitters and absorbers (and so best reflectors) are shiny and white.
Mobile phones use microwave signals
Properties of infrared radiation include: heats the surface of the food and is reflected by shiny surfaces.
Infrared is absorbed only by particles on the surface of the food increasing their energy.
This energy is then transferred to the rest of the food by conduction and convection.
Properties of microwave radiation include: they penetrate (about 1cm) into food, are reflected by shiny metal surfaces, can cause burns when absorbed by body tissue and can pass through glass and plastics.
Water and fat absorb microwaves
Microwaves are absorbed only by water and fat in the outer layers of the food increasing their KE.
When microwaves transmit information there is some signal loss due to interference, the curvature of the earth, no diffraction around objects and adverse weather.
The evidence of dangers from mobiles is not conclusive
Therefore it is not easy to decide on the siting of phone masts
As you increase the frequency of a microwave the energy increases
Analogue signals have a continuously variable value
Analogue signals have a continuously variable value
Digital signals are either on (1) or off (0)
Everyday uses of infrared radiation include: remote controls and short distance data links.
Infrared sensors detect body heat.
The advantages of using digital signals include: that it is easier to remove noise and you can use multiplexing.
Multiplexing is when you send more than one signal on a carrier wave
The advantages of using optical fibres include: multiplexing and lack of interference in the final signal.
Wireless technology uses electromagnetic radiation
The advantages of wireless technology are: no external/direct connection to a telephone needed, portable and convenient, allows access when on the move.
The advantages of DAB radios are: more stations available, less interference with other broadcasts
The advantages of DAB radios are: more stations available, less interference with other broadcasts
The disadvantages of DAB radios are: poorer quality compared to FM, not all areas covered.
Radiation used for communication is refracted and reflected and this can be an advantage or disadvantage for good reception
Common uses of wireless technology include: TV and radio, mobile phones and laptop computers.
Radio waves (like light) exhibit total internal reflection.
Shock waves from earthquakes can be detected by seismometers and recorded on a seismograph.
Shockwaves from earthquakes can cause damage to buildings and the Earth’s surface and tsunamis.
P waves are longitudinal
P waves travel through both solids and liquids
S waves are transverse
S waves only travel through solids.
P waves travel faster than S waves.
Exposure to UV radiation can cause: suntan, sunburn; skin cancer, cataracts and premature skin aging.
Sunscreens can reduce damage to skin.
SPF stands for Sun protection factor.
Darker skins have lower cancer risk as they absorb more ultraviolet radiation so less UV reaches the underlying tissues.
The ozone layer protects the Earth from ultraviolet radiation
Scientists were surprised to find the ozone hole
The ozone layer has been depleted by environmental pollution from CFCs.
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- Science Mapa Mental sobre Physics 1, creado por Lindis Dixon el 03/09/2016.
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- Lindis Dixon
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