Govt. Exams
Conservation of mass number: 14 + 4 = 17 + A → A = 1. Conservation of atomic number: 7 + 2 = 8 + Z → Z = 1. But Z = 0 for neutron. Correction: 7 + 2 = 8 + Z → Z = 1, which is a proton. But mass number gives 18 = 17 + 1. Need neutron.
In Bohr's model, angular momentum is quantized as L = mₑvr = nℏ, where n = 1, 2, 3... and ℏ = h/2π.
In beta-minus decay, a neutron converts to a proton, so atomic number (Z) increases by 1. Mass number (A) remains unchanged.
Total binding energy = (Binding energy per nucleon) × (Mass number) = 8.8 × 256 ≈ 2253 MeV ≈ 2250 MeV.
Gamma rays have the highest penetrating power due to their high energy and lack of charge. Beta particles have moderate penetrating power. Alpha particles have the lowest penetrating power.
Ionization energy of hydrogen = 13.6 eV. A photon with exactly 13.6 eV provides just enough energy to ionize, leaving zero kinetic energy for the electron.
α-particle: charge = 2e, mass = 4u. Proton: charge = e, mass = u. (e/m)ₐ/(e/m)ₚ = (2e/4u)/(e/u) = 1/2
rₙ = n²a₀, where a₀ is Bohr radius (0.53 Å). Orbital radius is proportional to n².
Since c = fλ, we have f = c/λ. Therefore E = hf = hc/λ
Compton scattering shows that photons behave as particles with momentum, providing evidence for particle nature of light. Wavelength shift Δλ = (h/mₑc)(1 - cosθ).
