Physics · Heat transfer: conduction, convection and radiation
Two spheres of the same metal have radii and and temperature and respectively. T
Two spheres of the same metal have radii \( 1 \mathrm{m} \) and \( 4 \mathrm{m} \) and temperature \( 4000 K \) and \( 2000 K \) respectively. The ratio of the energy radiated per second by the first to the second is :
- A. 1:
- B. 1:
- C. 2:
- D. 1:
Step-by-step solution
Using Stefan-Boltzmann law, power radiated P = εσAT⁴. Since spheres are same metal, ε same. Area A ∝ r², so P ∝ r² T⁴. Ratio P₁/P₂ = (r₁/r₂)² × (T₁/T₂)⁴ = (1/4)² × (4000/2000)⁴ = (1/16) × (2)⁴ = 16/16 = 1. Hence ratio 1:1.
Related MCQs
- The excess temperature of a body falls from to in 5 minutes, then the time to fall the excess temperature from to is (assume the Newton's co…
- Thermal radiations are similar to…
- A hot liquid is kept in a big room. The logarithm of the numerical value of the temperature difference between the liquid and the room is pl…
- The moving air from the hair dryer removes the molecules of liquids as soon as they escape from the surface of your hair. Which factor of ev…
- An instrument used to measure high temperature is…