Kinetic Theory
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Question : 7
Total: 14
Estimate the average thermal energy of a helium atom at (i) room temperature (27°C), (ii) the temperature on the surface of the Sun (6000 K), (iii) the temperature of 10 million kelvin (the typical core temperature in case of a star).
Solution:
The average kinetic energy of the gas at a temperature T
E =
k T
wherek = 1.38 × 10 − 23 J K − 1
T = Temperature in kelvin
(i)T = 27 ° C = 27 + 273 = 300 K
E =
× 1.38 × 10 − 23 × 300 = 6.21 × 10 − 21 J
(ii)T = 6000 K
E =
× 1.38 × 10 − 23 × 6000 = 1.242 × 10 − 19 J
(iii)T = 10 × 10 6 K = 10 7 K
E =
× 1.38 × 10 − 23 × 10 7 = 2.07 × 10 − 16 J
where
T = Temperature in kelvin
(i)
(ii)
(iii)
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