PYQ Vault
EbooksTutor

Power radiated by a hot body (Stefan-Boltzmann law)

This type of question, asked 2 times: 22 Jan 2025, 7 Apr 2025. All 2 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    22 Jan 2025

    5
    Two spherical bodies of same materials having radii 0.2 m and 0.8 m are placed in same atmosphere. The temperature of the smaller body is 800 K and temperature of bigger body is 400 K . If the energy radiate from the smaller body is E , the energy radiated from the bigger body is (assume, effect of the surrounding to be negligible)

    Tap an option to check your answer.

  2. Question 2

    7 Apr 2025

    24
    A wire of length 10 cm and diameter 0.5 mm is used in a bulb. The temperature of the wire is 1727∘C1727^{\circ}C and power radiated by the wire is 94.2 W . Its emissivity is x8\frac{x}{8} where x=x = ____\_\_\_\_ (Given σ=6.0×10−8 W m−2 K−4,π=3.14\sigma = 6.0 \times 10^{- 8}\text{ }W{\text{ }m}^{- 2}{\text{ }K}^{- 4},\pi = 3.14 and assume that the emissivity of wire material is same at all wavelength. )