Nuclear energy

What is nuclear fusion?

when two small nuclei join together to produce a larger nucleus, releasing energy in the process

What are the nuclei used in earth for nuclear fusion

deuterium + tritium → helium

What is nuclear fission?

when a neutron collides with a large unstable nucleus, splitting it into 2 smaller daughter nuclei and some neutrons.

How is energy released in nuclear fission?

the energy is transferred from the nuclear store of the nucleus to the kinetic store of the fission products

How does a chain reaction in nuclear fission work?

the neutrons released in fission go onto to collide with other nuclei and the fission process repeats

What are possible nucleus used for nuclear fission?

uranium 235 and plutonium

What do control rods do?

absorb neutrons without becoming unstable themselves

How do you use control rods?

lowering = decrease of rate of fission, raising = increasing of rate of fission

What do moderators do?

slow down neutrons, by colliding with them, so they lose momentum

Explain shielding in a nuclear reactor

the entire reactor is surrounded by shielding materials to absorb any radioactive emissions from the reactions

What does fusion require?

extremely high temperatures

The mass of the fused nucleus is less than the mass of the reactants, why?

mass is released as energy or radiation

What is the equation linking mass and energy in terms of fusion

E = mc squared

What do all the things in E = mc squared stand for

energy = mass x speed of light squared

Fusion is the source of energy in stars, what are the conditions for it to happen on stars

high temperature, high density

Why do stars even do nuclear fusion?

to produce an outward force due to energy release that will counteract the inward pull of gravity