Question

The temperatures of two bodies A and B are
respectively 727°C and 327°C. The ratio HA:Hg of
the rates of heat radiated by them is
(a) 727: 327
(b) 5:3
(c) 25:9
(d) 625:81​

Answer 1

Explanation:

as per Stefan Boltzmanns law heat radiated by a body is proportional to 4th power of its absolute temperature.

for body A Ta = 727℃ = 1000 °k

for body B Tb = 327 ℃= 600 °k

therefore Ha/Hb = (Ta^4)/(Tb^4)

= (1000^4)/(600^4)

= 7.716:1

but from option, last option d i.e 625:81 matches exactly with the answer obtained above.

Answer 2

Answer:

625:81

Explanation:

for body A Ta = 727℃ = 1000 °k

for body B Tb = 327 ℃= 600 °k

therefore Ha/Hb = (Ta^4)/(Tb^4)

= (1000^4)/(600^4)

= 7.716:1

but from option, last option d i.e 625:81 matches exactly with the answer obtained above.