Nikau traces a chain-reaction diagram with one finger: fission marks branching to the right, neutron circles connecting each split to the splits it causes. The whole story of a chain reaction sits in one drawing. This lesson reads it, count by count.
You have seen the chain reaction: nearby nuclei absorb one fission's neutrons and split in turn. A chain-reaction diagram draws that story. Reading one takes three counts: find each fission event, count the neutrons each fission releases, and count the fissions in each generation.
A chain-reaction diagram shows fission events connected by the neutrons that trigger them.
Each fission event is drawn once, with its released neutrons leaving it.
The fissions that one round of neutrons triggers form one generation.
Read one: find each fission event.
Read two: count the neutrons each fission releases.
Read three: count the fissions in each generation.
So the generations run 1, then 3, then 9: the third generation shows nine fissions.
In a chain-reaction diagram, every fission releases three neutrons and every neutron triggers a new fission. The diagram starts from one fission. How many fissions does the third generation show?
The first generation is the single starting fission.
That fission's three neutrons each trigger a fission, so the second generation shows 3 fissions.
Each of those 3 fissions releases three neutrons, so the third generation shows 3 × 3 = 9 fissions.
The third generation shows 9 fissions.
A chain-reaction diagram shows 1 fission, then 2 fissions, then 4 fissions. Every released neutron triggers a new fission. How many neutrons does each fission release?
From the one starting fission, the diagram jumps to 2 fissions, so that fission's neutrons triggered 2 fissions.
Every neutron triggers a fission, so each fission released 2 neutrons.
Check against the next generation: 2 × 2 = 4 fissions, and the diagram shows 4.
Each fission releases 2 neutrons.
In a chain-reaction diagram, every fission releases four neutrons and every neutron triggers a new fission. The first generation is one fission. How many fissions does the second generation show?
In the same kind of diagram, every fission releases four neutrons and every neutron triggers a new fission. The second generation shows 4 fissions. How many fissions does the third generation show?
In a chain-reaction diagram, every fission releases two neutrons and every neutron triggers a new fission. The diagram starts from one fission. How many fissions does the fourth generation show?
A chain-reaction diagram's first drawn generation shows 2 fissions. The next generation shows 6 fissions, and the one after shows 18. Every released neutron triggers a new fission. How many neutrons does each fission release?
The same diagram shows exactly three generations: 2 fissions, then 6, then 18. How many fission events does the whole diagram show?
In a chain-reaction diagram where every neutron triggers a new fission, which fissions make up one generation?