Climbing the binding energy curve
"Climbing the binding energy curve" is a free, interactive Class 12 Physics simulation for NEET and JEE, built on the lesson "Binding energy curve" in Nuclei. Choose split (one nucleus into two equal halves) or join (two equal nuclei into one), then slide A. Orange is what goes in, green is what comes out. Energy comes out whenever nucleons move up the curve: heavy nuclei split towards the middle, light nuclei join towards it. Q = (number of nucleons) × (gain in Ebn). JEE Main asked 38 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
From the lesson Binding energy curve in Nuclei. Change the values and watch what happens.
In JEE Main
42 shifts analysed
38 questions from Nuclei across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §13.4.2
- Fig. 13.1 plots the binding energy per nucleon Ebn against the mass number A for many nuclei.
- For middle-mass nuclei, 30 < A < 170, Ebn hardly changes with A. The curve peaks at about 8.75 MeV for A = 56 and falls to 7.6 MeV at A = 238.
- Ebn is lower for light nuclei (A < 30) and for heavy nuclei (A > 170).
- Conclusion (i): the force binding nucleons is attractive and strong enough to give a few MeV per nucleon.
- Conclusion (ii): the flat middle means the force is short-ranged. A nucleon deep inside a big nucleus feels only the neighbours within range. If it can have at most p of them, its binding is about pk, k being a constant energy. Adding more nucleons far away does not change it, and most nucleons of a large nucleus are inside, not on the surface.
- This is the saturation property of the nuclear force: each nucleon affects only nucleons close to it.
- Conclusion (iii): a nucleus of A = 240 has lower Ebn than one of A = 120. If it splits into two A = 120 nuclei, the nucleons end up more tightly bound and energy is released: fission.
- Conclusion (iv): two very light nuclei (A ≤ 10) joining into a heavier one also end up with higher Ebn, again releasing energy: fusion, the energy source of the sun.
- The curve is smooth, but it shows peaks at nuclides such as ⁴He and ¹⁶O, which is taken as evidence of an atom-like shell structure in nuclei.
Questions
3 answers
- What does the "Climbing the binding energy curve" simulation show?
- Choose split (one nucleus into two equal halves) or join (two equal nuclei into one), then slide A. Orange is what goes in, green is what comes out.
- Does JEE Main ask questions from Nuclei?
- Yes. JEE Main asked 38 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
- Is this simulation free?
- Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Binding energy curve" in Nuclei (Class 12 Physics).
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