Chaptet 7 - Energy From The Nucleus Flashcards
Describe the process of nuclear fission
A neutron is absorbed which splits the nucleus into two, which releases 2 or 3 neutrons and energy is released.
What is a chain reaction
When each fission event causes further fission events.
What is nuclear fusion
The process of forcing two nuclei close enough together so they form a single larger nucleus
How can nuclear fusion be brought about
By making two light nuclei collide at very high speed
By what process is energy released in stars
Nuclear fusion
Why will nuclei approaching each other repel on another
They will repel due to their positive charge
What can be done to overcome the two nuclei repelling one another
The nuclei must be heated to w very high temperature to give them enough energy to overcome t the repulsion and fuse.
What is the problem with producing energy from nuclear fusion in reactors
Because of the enormously high temperatures involved, the reaction cannot take place in a normal container but has to be contained by a magnetic field
What is the major source of background radiation
Radon gas. It seeps through the ground from radioactive substances in rocks deep underground
What are the ways of reducing exposure to nuclear radiations
- Keep as far as possible from sources of radiation
- Spend as little time exposed as possible
- Shield themselves with materials such as concrete and lead
What happened to the temperature of the universe as it expanded
It’s temperature fell
Why was dust and gas pulled together in the early universe
It was pulled together by gravitational attraction to form stars. The resulting intense heat started off nuclear fusion reactions in the stars so they began to emit visible light and other radiation
What is a galaxy
A collection of billions of stars held together by their own gravity
What is a protostar
A gas and dust cloud in space that can go on to form a star
Why do stars radiate energy
Because of the hydrogen fusion in the core
