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#conceptual physics

4 public questions tagged with this topic.

Which of the following statements is incorrect about Rutherford’s nuclear model?

**Stability** belt of stability N≈Z for light, N>Z for heavy due to Coulomb, beyond leads to alpha decay, fission, stability requires balance, nuclear force saturated explains constant density and BE/A. Rutherford’s model does not explain atomic stability, as it predicts electrons would emit radiation and collapse into the nucleus, not maintain stable orbits. Using E_n = -13.6/n² eV, r_n = n² a₀, L = n h/2π, R = R₀ A^¹/³, BE = Δm c² and 1 u = 931.5 MeV, evaluation yields Electrons maintain stable orbits without radiating, consistent with Bohr model and nuclear binding energy systematics.

Ref: NCERT > Physics Book > Atoms and Nuclei > Radioactive Decay, Nuclear Forces and Stability

Which of the following statements is correct about gravitational potential energy?

V = −GMmr, which is negative for bound systems and decreases (becomes more negative) as r decreases, making option 3 correct. As per NCERT, applying relevant law/formula with correct units and sign convention leads to It becomes more negative as objects approach. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.