NEET UG 2007 — Thermodynamics

If the cold junction of thermocouple is kept at $0^{\circ} \mathrm{C}$ and the hot junction is kept at $T^{\circ} \mathrm{C}$, then the relation between neutral temperature $\left(T_n\right)$ and temperature of inversion $(T)$.

Assuming the sun to have a spherical outer surface of radius $r$, radiating like a black body at temperature $t^{\circ} \mathrm{C}$, the power received by a unit surface, (normal to the incident rays) at a distance $R$ from the centre of the sun is: where $\sigma$ is the Stefan's constant

An engine has an efficiency of $1 / 6$. When the temperature of sink is reduced by $62^{\circ} \mathrm{C}$, its efficiency is doubled. Temperatures of the source is:

A black body is at $727^{\circ} \mathrm{C}$. It emits energy at a rate which is proportional to: