Bimetallic strip consists of two metals with different coefficients of linear expansion. On heating, one expands more, causing bending. Used in thermostats, fire alarms. Expansion difference causes curvature.
Explanation:
Bohr model: radius r_n = (4πε₀ħ²n²)/(m_e e²) = n² a₀, where a₀ is Bohr radius (≈0.529 Å). Thus r_n ∝ n². Energy E_n ∝ -1/n². Memory tip: 'Bohr radius: r ∝ n²; energy: E ∝ -1/n²'. This atomic physics formula is frequently tested in competitive exams. Always recall that n is principal quantum number; higher n means larger orbit, less tightly bound electron. This problem assesses understanding of quantization in early quantum theory.
Explanation:
At maximum height, vertical velocity = 0 momentarily, but acceleration = g downward throughout motion. Memory tip: 'Peak: v=0, a=g; gravity never switches off'. Kinematics concept frequently tested to correct misconception that acceleration vanishes at peak.
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