I keep getting “Mass defect and binding energy” questions wrong in Nuclei. What's the trap?
subtracting masses in the wrong direction and obtaining negative binding energy.
The usual trap: subtracting masses in the wrong direction and obtaining negative binding energy. How to avoid it: separated nucleons minus nucleus gives positive mass defect. Go back to the definition — A bound nucleus has less mass than its separated nucleons. The missing mass corresponds to the energy released during binding: B = Delta m c^2.
Key point
Mass defect and binding energy
Common mistake
subtracting masses in the wrong direction and obtaining negative binding energy.
Memory tip
separated nucleons minus nucleus gives positive mass defect.
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