Atoms — Class 12 Physics NCERT Solutions (Free)
Free step-by-step NCERT solutions for Class 12 Physics chapter "Atoms" — 6 important questions with detailed answers for CBSE board exam preparation.
TL;DR: Free step-by-step NCERT solutions for Class 12 Physics chapter "Atoms" — 6 important questions with detailed answers for CBSE board exam preparation.
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Key Questions Covered:
- Explain Bohr's model of hydrogen atom. Derive expression for energy levels an…
- An electron in hydrogen atom transitions from n = 3 to n = 1. Find the energy…
- What are X-rays? Explain characteristic and continuous X-ray spectra.
- + 3 more questions in the full chapter
Solutions Summary:
| Question | Status |
|---|---|
| Explain Bohr's model of hydrogen atom. Derive expression … | ✓ Solved |
| An electron in hydrogen atom transitions from n = 3 to n … | ✓ Solved |
| What are X-rays? Explain characteristic and continuous X-… | ✓ Solved |
Showing 3 of 6 questions
Q1: Explain Bohr's model of hydrogen atom. Derive expression for energy levels and radius of orbit.
Bohr's Model (1913):
Atom with nucleus at center and electrons in circular orbits, combining classical mechanics with quantum postulates.
Postulates:
1. Electron moves in circular orbit without radiating energy
2. Only orbits with angular momentum L = nℏ are allowed (n = 1, 2, 3, ...)
where ℏ = ...
Q2: An electron in hydrogen atom transitions from n = 3 to n = 1. Find the energy and wavelength of photon emitted.
Given:
Initial state: n_i = 3
Final state: n_f = 1
Energy levels: E_n = -13.6 eV/n²
Energy of Initial Level:
E₃ = -13.6/3² = -13.6/9 = -1.51 eV
Energy of Final Level:
E₁ = -13.6/1² = -13.6 eV
Energy of Emitted Photon:
ΔE = E_f - E_i = E₁ - E₃
ΔE = -13.6 - (-1.51) = -13.6 + 1.51 = -12.09 eV
The e...
Q3: What are X-rays? Explain characteristic and continuous X-ray spectra.
X-rays: Electromagnetic radiation produced when high-energy electrons strike a metal target, with wavelengths 0.1-100 nm.
Production:
1. Electrons accelerated through high potential difference (10 kV - 100 kV)
2. Directed at metal target (Cu, Mo, W, etc.)
3. Electrons decelerate and lose energy
4. ...
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