how is heat transferred from place to place?
conduction, convection, radiation
What surface is better at absorbing heat?
dark matt
... [Show More] surfaces
what surface is better at reflecting heat?
light shiny surfaces
what objects emit infared radiation?
all objects. the hotter it is, the more it emits.
what does infared radiation involve?
waves! not particles
what can radition pass through?
vaccum
particles in solids, liquids and gases have ? amounts of energy
different
describe the particles in a solid
close together particles, with a regular pattern.They vibrate and stay in a fixed position
describe the particles in a liquid
close particles with a random patter. Move around eachother
describe the particles in a gas
far apart, random pattern, move quickly and in any direction
what is conduction
when heat energy moves through a substance
are metals, or non metals better conductors
metals
what are non metals and gases
good insulators
the hotter the metal is...
the more kinetic energy the vibrations have
what happens in convection
particles with lots of heat energy get less dense and rise, replacing particles with less heat energy.
what is it called when a liquid changes to a gas?
evaporation
what is it called when a gas changes to a liquid
condensation
what increases condensation rate?
increase in temperature of gas
what increases rate of evaporation?
increase in temperature of liquid, increase surface area, air moving over liquids surface
the bigger difference in temperature between object and surroundings...
the greater rate of heat energy is transferred
small animals have
large surface area to volume ratio
if small animals have a large surface area to volume ratio
they lose heat to surroundings easily and have to eat more to replace energy lost
large animals have
a small surface area to volume ratio
if large animals have a small surface area to volume ratio
they lose little heat to surroundings and may risk over heating
what enables elephants to cool down quickly
large ears
lower u-value means
better heat insulator
what does temperature mean
measure of how hot an object is
what does heat mean
measure of thermal energy contained
temperature increase depends on
mass of an object, substance it is made from, amount of energy transferred to the obect
what are forms of energy
magnetic, kinetic, heat, light, gravitational potential, electrical, elastic potential, nuclear
what diagram shows the useful and wasted energy
sankey diagram
what are fossil fuels
coal, oil, natural gas
what are advantages of fossil fuels
they are reliable and quick
what are disadvantages of fossil fuels
supply is limited, coal and oil release sulphur dioxide, release carbondioxide when burned, increases global warming,
what releases the most carbon dioxide, coal or natural gases?
coal
example of a nuclear fuel
uranium, plutonium
advantages of nuclear fuels?
dont produce sulphur dioxide or carbon dioxide
disadvantages of nuclear fuels?
non renewable, radioactive material released if there is an accident which would damage health
what is wind energy?
wind blows into wind turbines, causing them to turn and drive a generator
what are the types of water energy?
wave, tides, hydroelectric power
what is wave energy
kinetic energy in waves drive electricity generators
what is tide energy
tidal barrage is built over a river to make use of kinetic energy in moving water. barrage contains electricity generators which are driven by water rushing through tubes in the barrage
what is hydroelectric power?
moving water drives electrical generators which are built inside dams
advantages of water power?
no fuel costs, no harmful gases, reliable, easily switched on
disadvantages of water power?
hard to produce large amounts of electricity, tidal barrages destroy habitats, hydroelectricity floods farmland, rotting vegetation under water releases methane, a greenhouse gas
what is geothermal energy?
hot water and steam underground is used to drive turbines
how does geothermal energy work in volcanic areas?
rocks contain radioactive substances, rocks heat water so it rises to surface naturally, steam and hot water drives turbines and electricity generators
how does geotheraml energy work in hot rocks?
hot water and steam doesnt rise to the surface, deep wells drilled down to hot rocks and cold water is pumped down to condense the water, hot water rises and can be used to drive turbines and electricity generators
advantages of solar energy?
renewable, provides energy in remote locations
disadvantages of solar energy?
inefficient, doesnt work at night
how is electricity distributed from power stations to consumers?
the national grid
what does a step up transformer do
steps up voltage
what does a step down transformer do
decreases the voltage
how do you work out the speed of a wave
frequency plus wavelength
what is a transverse wave?
where the vibrations (oscillations) are at right angles to the direction of travel
what speed does light travel at, through a vaccum?
the same speed
what is a longitudinal wave?
oscillations are along the same direction as travel
what is amplitude
the maximum disturbance from undisturbed position
what is wavelength
length from one chord (bump) to the other
what is frequency
number of waves produced by a source each second
what happens to sound and light waves when they cross a boundary with different densities, e.g air and glass
they change speed and change direction
what is diffraction
when waves meet gap in barrier and they carry on through but more spread out
if the gap in diffraction is larger than the wavelength what happens
it doesnt spread very much and causes a sharp shadow
what happens in diffraction if the gap is similar to the wavelength
it causes a lot of spreading with little shadow
what waves reflect from surfaces
sound and light waves
where is the angle of incidence
between the incident (incoming ray) and the normal
where is the angle of reflection
between the reflected ray and the normal
what type of echo does a smooth surface produce when a sound wave hits it?
strong echo
where can waves appear to be coming from?
a point beyond the mirror
the angle of incidence is the same as the...
angle of reflection
are sound waves longitudinal or transverse?
longitudinal
what direction do vibrations occur in?
same direction as travel
the greater the amplitude of an object...
the louder the sound
the greater frequency of an object...
the higher the pitch
what does an object / substance produce when it vibrates?
sound
what is the electromagnetic spectrum?
white light split into prism to form a spectrum
what speed do all forms of electromagnetic radiation travel at?
the same speed
when was the big bang thought to have happened?
13.7 billion years ago
what is the big bang theory?
origin in all matter of universe was concentrated to a single tiny point and then expanded rapidly into a huge explosion
what is the dopplar effect?
when a source travels towards you the wavelength decreases and the frequency increases, when a source travels away from you the wavelength increases and the frequency decreases
what happens to the source in the dopplar effect when it moves away from you
the wavelength increases and the frequency decreases
what direction are distant galaxies moving from us?
away from us
the further away a galaxy is...
the faster it is moving
what does CMBR mean?
microwaves coming from every direction in space [Show Less]