JEE · Physics · Nuclei doubts
8 doubts found
A sample has passed through three half-lives. Why is the amount left one-eighth, not zero?
A half-life removes the same fraction, not the same amount.
How do I decide whether a nuclear reaction releases energy using atomic masses?
Calculate Q = (total initial mass - total final mass)c^2.
What does “Nuclear size and density” actually mean in Nuclei, and why does it matter for JEE?
Nuclear radius scales as R = R_0 A^(1/3), so volume scales with nucleon number A. Because mass also scales with A, nuclear density is approximately constant across nuclei.
I keep getting “Nuclear size and density” questions wrong in Nuclei. What's the trap?
thinking a nucleus with twice the nucleons has twice the radius.
What does “Mass defect and binding energy” actually mean in Nuclei, and why does it matter for JEE?
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.
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.
What does “Binding energy per nucleon” actually mean in Nuclei, and why does it matter for JEE?
Binding energy per nucleon measures average tightness of binding. Its curve rises toward iron/nickel and then slowly falls, explaining why both fusion of light nuclei and fission of heavy nuclei can release energy.
I keep getting “Binding energy per nucleon” questions wrong in Nuclei. What's the trap?
using total binding energy alone to compare nuclear stability.