Thermal diffusivity α is defined as:
A{'text': '$\\alpha = k$', 'label': 'A'}
B{'text': '$\\alpha = k/(\\rho c_p)$ (m²/s) — ratio of conduction transport to thermal storage capacity', 'label': 'B'}
C{'text': '$\\alpha = h/k$', 'label': 'C'}
D{'text': '$\\alpha = c_p T$', 'label': 'D'}
Answer & Solution
Correct answer: B. {'text': '$\\alpha = k/(\\rho c_p)$ (m²/s) — ratio of conduction transport to thermal storage capacity', 'label': 'B'}
α = k/(ρc_p), m²/s. Appears in the heat equation: $\partial T/\partial t = \alpha \nabla^2 T + \dot{q}/(\rho c_p)$. Materials with high α (metals) respond quickly to temperature changes; insulators have low α.
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