CBSE Class 12 · 2007 · Modern PhysicsShort Answer

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Draw a plot of the potential energy of a pair of nucleons as a function of their separation. What is the significance of the negative potential energy in the graph drawn?

Answer: Negative PE indicates the nucleons attract each other (bound system).

Solution

The potential energy is strongly positive (repulsive) for separations below about

0.8 fm

, falls to a minimum of about

- 100 MeV

near

r_{0} \approx 0.8 fm

, and rises towards zero for larger separations (see figure).
The negative potential energy signifies that the nuclear force between the nucleons is attractive in this region, which binds them together into the nucleus.

Negative PE \Rightarrow attractive (binding) nuclear force

CBSE Class 12 Board · 2007 · Subjective

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