physics 4 (paper1)

define Nuclear Fission

splitting a large, unstable nuclease

what is nuclear fission used for?

to release energy from a large atom by splitting them into smaller atoms

what is released when nuclear fission occurs?

two or three neutrons

what has to happen first before nuclear fission can take place?

to atom has to absorbs a neutron first

how do chain reactions happen in nuclear fission?

where a slow-moving neutron is absorbed by another atom and the process repeats.

when energy is released what happens to the energy that does not go to the kinetic store?

gets taken by gamma rays

what can remaining neutrons be used for?

heat water, making turbines spin for generators

what can be used to control nuclear fission?

control rods

why might you use control rods?

to stop the reaction happening too fast as if it is uncontrolled it will release too much energy and lead to an explosion

true or false, nuclear fission is used to make nuclear weapons?

true

define nuclear fusion

the joining of small nucli

how does nuclear fission take place?

two light nucli colliding at a high speed and joining

what do hydrogen nucli join to create?

helium nucleas

true or false, when joined the heavier nucleas will have more mass than the two sperate nucli?

false

does nuclear fission or fusion release more energy?

fusion

what are some disadvantages of using nuclear fusion?

it is expensive, the reactors are incredibly hard to build as high temperatures and pressures are needed

what are alpha particles?

helium nuclei

how does alpha radiation happen?

when an alpha particle is emitted from the nucleas

what are 3 features of alpha particles?

dont penetrate far
absorbed by paper
strongly ionising

what are beta particles?

high speed electrons

how does beta radiation take place?

a fast moving electron released by the nucleas

what are five features of beta particles?

no mass
charge -1
moderately ionising
penetrate moderately
absorbed by aluminium

what happens when a beta particle is emitted?

a neutron turns into an electron

what are gamma rays?

electromagnetic radiation released by a nucleas

what are three features of gamma rays?

penetrate far
weakly ionising as they pass through instead of colliding
absorbed by thick sheets of lead or meters of concrete

what is the equation for radioactive decay?

atom before decay= atom after decay+ radiation symbols

how are gamma rays used for medical trackers?

they are injected into the body and it travels round, being tracked by an external detector. when absorbed by that part of the body, they detector will see if it is absorbing it correctly

how are gamma rays used to treat cancer?

radiotherapy- kill all the cancer cells and damage some normal ones in the process

what are uses of radio activity?

thickness control

sterilisation

smoke alarm

industrial tracer

explain the process of radio activity and thickness control

is controlled by Beta particle, by how much passes through paper to a geiger counter. the counter then controlls the pressure of the rollers

explain the process of sterilisation through radio activity

after packing gamma rays are used to remove any bacteria from food. it is also used to remove any microorganisms before hospital equipment is reused.

explain how smoke alarms work using nuclear activity

radioisotope Americium-241 with a half life of 460years. emits alpha particles that ionise air around them. when smoke goes inside alpha particles are absorbed making the current fall, setting off the alarm

explain how radio activity is used with industrial tracers

radioisotoped detect faulty pipes. a gamma source is one side and a photographic film on the other, this will show any cracks

how do you check thyroid?

drink iodine, then x-rays show radiation