Physics

examples of chemical energy stores

fuels, foods, and battery chemicals

how can energy be transferred

heating, waves, electric current or force moving an object

ways of heating a house

cavity wall insulation, double glazing, thick bricks with low thermal conductivity

to reduce the rate of thermal energy transfer, the insulating material used should:

have as low a thermal conductivity as possible and be as thick as possible

black body radiation

a radiation emitted by a perfect black body, a body that absorbs all the radiation that hits it

the earth’s temperature is affected by:

level of absorption and emission of infrared radiation from the sun into the earth’s surface and atmosphere

how do geothermal power stations work

water is pumped onto hot rocks underground to produce steam, which drives turbines at the earth’s surface

nuclear power advantages

don’t produce greenhouse gases, fuel transfers much more energy per kilogram than fossil fuels

static electricity

when you rub 2 electrically insulating materials together, electrons are rubbed off one material and deposited to the other

what happens when more resistors are added in the series (resistance)

increases the total resistance because the current is reduced and the total p.d. is unchanged

how dense does an object have to be to float in water

under 1000kg/m^3

how does an unstable nuclei become stable

by emitting radiation

strongest radiation ranking high to low

gamma, beta, alpha

what can radioactive tracers be used for

measure the flow of a substance through an organ

induced fission

when a neutron is absorbed by a uranium or plutonium nucleus

force

push or pull that acts on an object due to its interaction with another object

resolving force

finding perpendicular components that have a resultant force that is equal to the force

inertia

the tendency to stay at rest or in uniform motion

primary seismic waves

longitudinal, cause initial tremors, refract at the boundary between mantle and core

secondary seismic waves

transverse, slower than primary waves, can’t travel through liquid core of the earth

why do both types of seismic waved bend as they travel through the mantle

their speed gradually changes

long waves

slower than both seismic waves, only travel in the earth’s crust, arrive last and causes violent movement of earth’s crust

what does the frequency of waves affect

how far they travel, how much they spread, how much information they carry

what are gamma rays used for

kill bacteria in food, sterilise equipment, killing cancer cells

how do stars produce all other naturally occurring elements

fusion occurs at high temperatures, which produces new elements, hydrogen nuclei fuse to form helium nuclei, which fuses to make heavier elements up to iron

Describe the relationship between the distance from the earthquake to the seismometer and the time between the P-wave and the S-wave arriving.

the distance is directly proportional to the time between the two waves arriving at the seismometer

one medical use of gamma rays

medical imaging

why can gamma rays be harmful but radio waves can’t

gamma rays are ionising which can cause mutations in dna which can cause cancers

what happens when a current flows through a wire

a magnetic field is formed

what is the first finger used to show in the left hand rule

the magnetic field between the poles

what was the second finger used to show in the left hand rule

the direction of current through the wire

what is the thumb used to show in the left hand rule

the force acting on the wire

when and who did the alpha particle scattering experiment

Rutherford in 1909

who made the nuclear model

Bohr

when and who discovered the neutron

chadwick in 1932

which radiation has the highest irradiation levels

gamma

which radiation has the highest ionising and contamination levels

alpha

when and what did john dalton agree with democritus about

in 1804 they agreed that matter was made of of atoms that couldn’t be broken up

one use of alpha radiation

smoke alarms

how does alpha radiation work in smoke alarms

it ionises air particles causing current to flow. if there is smoke around, it binds to the ionised air and causes current to stop setting off the alarm

one use of beta radiation

test the thickness of metal sheets

how does beta particles test the thickness of metal sheets

beta particles penetrate further than alpha particles but not as much as gamma rays