Temperature increase by light absorption

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SUMMARY

The discussion focuses on calculating temperature increases in crystals due to light absorption. Key factors include the power of the radiated light, the reflection coefficient (ρ), and the heat capacity (C) of the crystal. Sciphys1 provides a formula for temperature change (ΔT) based on absorbed energy, stating that ΔT = (1-ρ)/C * ∫W(t)*dt, where W(t) represents the power of the light over time. This indicates that both theoretical calculations and experimental validation are necessary for accurate temperature rise assessments.

PREREQUISITES
  • Understanding of thermodynamics, specifically heat capacity
  • Knowledge of light absorption principles in materials
  • Familiarity with the concept of reflection coefficients in optics
  • Basic calculus for integrating power over time
NEXT STEPS
  • Research the principles of light absorption in different materials
  • Study the effects of reflection coefficients on energy absorption
  • Explore thermodynamic calculations involving heat capacity
  • Learn about experimental methods for measuring temperature changes in materials
USEFUL FOR

Physicists, materials scientists, and engineers interested in thermodynamics and optical properties of materials will benefit from this discussion.

sciphys1
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Hi,

I have a question. If a crystal absorbs light and the absorption process leads to some excess energy being released as heat . Can one calculate the temperature rise or an experiment would most certainly need to be done? Apart from the heat capacity of the crystal before light absorption ,what else would one need to know? Any discussion on this would be highly appreciated.

Thanks.

Sciphys1
 
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It will depend upon the power of radiated light, reflection coefficient and heat capacity, if you consider the case of a black body, then the radiated energy is W*t, ΔT = W*t/C, if you want a general case, then the absorbed energy Eabsorbed = (1-ρ)∫W(t)*dt, ρ is the reflection coefficient ΔT = (1-ρ)/C * ∫W(t)*dt
 

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