Key relationship
Q=(Σmi−Σmf)c²; power=rate × Q. Conserve A and Z.
Physics · Class 12
Fission and fusion energy balance
Nucleon number and charge balance before comparing masses. A positive Q is released energy for the specified products. Fusion and fission are different rearrangements but obey the same mass-energy accounting.
Open the interactive experiment →Fission and fusion energy balance
வினையில் நிறை எண்ணும் மின்சுமையும் காக்கப்படும். முன் மற்றும் பின் நிறைகளின் வேறுபாடு விடுவிக்கப்படும் ஆற்றலைக் கொடுக்கும்.
Key notes, relationships and model limits
Remember
Nucleon number and charge balance before comparing masses. A positive Q is released energy for the specified products. Fusion and fission are different rearrangements but obey the same mass-energy accounting.
Common trap
Positive Q alone does not guarantee ignition or a spontaneous reaction.
Model limits
Mass-sum Q values for the named channels; subsequent decays, neutron moderation, ignition conditions and reactor dynamics omitted. The fission channel is not a universal200 MeV value.
What you will learn
Balance a nuclear channel and calculate its Q value.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
D–T masses give about17.59 MeV; the specified Ba/Kr fission channel gives about173.3 MeV.
Why this matters
The model connects fission and fusion energy balance with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
A positive Q means the product rest-mass sum is?
- Larger
- Smaller
- Necessarily unchanged
Read the explanation
Q>0 requires Σmi>Σmf.
Course connection: Class XII Chapter 13. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.