In a closed room,heat transfer takes place by

If $120 \ J$ of thermal energy is incident on an area of $3 \ m^2$,the amount of heat transmitted is $12 \ J$,and the coefficient of absorption is $0.6$,then the amount of heat reflected is: (in $J$)

The ends of a metal bar of constant cross-sectional area are maintained at temperatures $T_1$ and $T_2$ which are both higher than the temperature of the surroundings. If the bar is unlagged,which one of the following sketches best represents the variation of temperature with distance along the bar?

$A$ heated body maintained at $T \ K$ emits thermal radiation of total energy $E$ with a maximum intensity at frequency $v$. The emissivity of the material is $0.5$. If the temperature of the body is increased and maintained at temperature $3T \ K$,then:
$(i)$ The maximum intensity of the emitted radiation will occur at frequency $v/3$.
$(ii)$ The maximum intensity of the emitted radiation will occur at frequency $3v$.
$(iii)$ The total energy of emitted radiation will become $81E$.
$(iv)$ The total energy of emitted radiation will become $27E$.

The dimensions of $\sigma b^4$, where $\sigma$ is Stefan's constant and $b$ is Wien's constant, are:

Differentiate clearly between thermal conduction,thermal convection,and thermal radiation.