Govt. Exams
11,460 years = 2 × 5730 years = 2 half-lives. After 2 half-lives: 1 × (1/2)² = 0.25 mg remains.
Bremsstrahlung (braking radiation) occurs when fast electrons are decelerated by the nucleus, producing continuous X-ray spectrum.
Alpha decay: A decreases by 4, Z decreases by 2. ²¹⁰₈₄Po → ²⁰⁶₈₂Pb + ⁴₂He. The resulting nucleus is Lead-206.
Higher binding energy per nucleon indicates greater nuclear stability. ⁵⁶Fe (8.79 MeV/nucleon) is more stable than ²³⁵U (7.59 MeV/nucleon).
Bohr's quantization condition states that angular momentum L = mvr = nh/(2π), where n is the principal quantum number.
Stopping potential Vs = (hf - W)/e, which depends directly on frequency. Intensity affects photocurrent, not maximum KE. Threshold frequency exists. Emission requires photon energy > work function.
When fast electrons knock out inner shell (K-shell) electrons, electrons from outer shells fall down, emitting characteristic X-rays specific to the target material.
Bohr's quantization condition: L = mvr = n(h/2π) = nℏ, where n = 1, 2, 3...
After 30 days = 3 half-lives. Remaining fraction = (1/2)³ = 1/8
In beta-minus decay, a neutron converts to a proton, emitting an electron and antineutrino. Atomic number increases by 1: Z = 6 + 1 = 7. The daughter nucleus is ¹⁴₇N.
