Kinetic Theory of Gases and Radiation
Kinetic Theory of Gases and Radiation
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See all →- Find the temperature of a blackbody if its spectrum has a peak at (a) λmax = 700 nm = 700×10^(-9 )m, (b) λmax = 3 cm = 3×10^(-2 )m, (c) λmax = 3 m b = 2.897 × 10⁻³ m K (a) T= b/λmax = (2.897 × 10⁻³ )/ (700×... 1
- A small-blackened solid copper sphere of radius 2.5 cm is placed in an evacuated chamber. Given : r = 2.5 cm = 2.5 ×10⁻²m, T₀ = 273+100 = 373 K, T = 273+110 = 383 K, σ = 5.76 × 10⁻⁸ J s⁻¹ m⁻² K⁻⁴ The rate at which energy must be s... 1
- Earth’s mean temperature can be assumed to be 280 K. Given: T = 280 K, Wien's constant b = 2.897×10⁻³ m.K λ_maxT = b λ_max = b /T = 2.897×10⁻³ / 280 = 1.035 ×10⁻⁵ m This value lies in the infra... 1
- Compare the rates of emission of heat by a blackbody maintained at 727 ºC and at 227ºC Given: T₁ = 273 + 727 = 1000 K, T₂ = 273 + 227 = 500 K, T₀ = 273 + 27 = 300 K i) The rate of emission of heat, dQ/dt = σAT⁴ we assume that t... 1
- The emissive power of a sphere of area 0.02 m2 is 0.5 kcal s-1 m-2. What is the amount of heat radiated Given : R = 0.5 kcal-s⁻¹ 'm⁻² , A =0.02 m², t=20s Q = RAt = (0.5) (0.02) (20) = 0.2 kcal 0.2 kcal is the required quantity. 1
- Energy is emitted from a hole in an electric furnace at the rate of 20 W, when the temperature of the furnace is 727 ºC. Given: Q/t = 20W, T=273+727=1000 K, σ = 5.7×10⁻⁸ Js⁻¹/m².K⁻⁴ Q/t = σAT⁴ ∴ The area of the hole, A = (Q/t)/(σT⁴ ) = 20(5.7×10⁻⁸ ×1000⁴ ) = 20... 1