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Rate of radiation when size, temperature or emissivity of a body changes

This type of question, asked 11 times: 10 May 2023 S1, 10 May 2023 S2, 12 May 2024 S1, 19 Apr 2025 S1, 21 Apr 2025 S1, 25 Apr 2025 S1, 26 Apr 2025 S2, 13 Apr 2026 S1, 15 Apr 2026 S2, 16 Apr 2026 S1, 12 May 2026 S2. All 12 questions below, oldest first.

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  1. Question 1

    10 May 2023 S1

    9
    A black sphere has radius RR whose rate of radiation is EE at temperature TT. If radius is made half and temperature 4T4T, the rate of radiation will be

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  2. Question 2

    10 May 2023 S2

    30
    Rate of radiation by a black body is 'R' at temperature 'T'. Another body has same area but emissivity is 0.2 and temperature 3T. Its rate of radiation is

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  3. Question 3

    12 May 2024 S1

    32
    A black sphere has radius RR whose rate of radiation is EE at temperature TT. If radius is made R/3R/3 and temperature 3T3T, the rate of radiation will be

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  4. Question 4

    19 Apr 2025 S1

    7
    Black sphere of radius R radiates power P at certain temperature T. If the temperature is doubled, the radius gets doubled. Now the power radiated would be

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  5. Question 5

    21 Apr 2025 S1

    3
    A rectangular block of surface area A emits energy E per second at 27∘C27^{\circ}C. If length and breadth is reduced to half of initial value and temperature is raised to 327∘C327^{\circ}C then energy emitted per second becomes

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  6. Question 6

    25 Apr 2025 S1

    2
    A rectangular black body of temperature 127∘C127^{\circ}C has surface area 4 cm×2 cm4\text{ }cm \times 2\text{ }cm and rate of radiation is E . If its temperature is increased by 400∘C400^{\circ}C and surface area is reduced to half of the initial value, then the rate of radiation is

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  7. Question 7

    26 Apr 2025 S2

    35
    A black sphere has radius RR whose rate of radiation is E at temperature T . If radius is made [R/2][R/2] and temperature 3T, the rate of radiation will be

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  8. Question 8

    13 Apr 2026 S1

    115
    A black rectangular surface of area A emits energy E per unit time at 27∘27^\circ C. If length and breadth is reduced to (14)th\left(\dfrac{1}{4}\right)^{th} of initial value and temperature is raised to 327∘327^\circ C, then energy emitted per unit time becomes

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  9. Question 9

    13 Apr 2026 S1

    114
    Rate of radiation by a black body is 'R' at temperature 'T'. Another body has same area but emissivity is 0.2 and temperature 3T. Its rate of radiation is

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  10. Question 10

    15 Apr 2026 S2

    113
    A black rectangular surface of area A emits energy E per second at 127∘127^\circC. If length and breadth is reduced to half of initial value and temperature is raised to 527∘527^\circC then energy emitted becomes

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  11. Question 11

    16 Apr 2026 S1

    116
    A black rectangular surface of area 'A' emits energy 'E' per second at 27∘27^\circC. If length and breadth is reduced to half of its initial value and temperature is raised to 327∘327^\circC then energy emitted per second becomes

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  12. Question 12

    12 May 2026 S2

    112
    A rectangular black body of temperature 27∘C27^\circ C has surface area 66 cm ×3\times 3 cm and rate of radiation EE. If its temperature is increased by 300∘C300^\circ C and its linear dimensions are reduced to (13)rd\left(\dfrac{1}{3}\right)^{rd} of their initial value then the rate of radiation is

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