Embibe Experts Solutions for Exercise 4: Assignment

A solid cylinder of length $L$ and radius $r$ is heated up to same temperature as that of a cube of edge length $a.$ If both have same material, volume and allowed to cool under similar conditions, then ratio of amount of radiations radiated will be (Neglect radiation emitted from flat surfaces of the cylinder)

A very thin metallic shell of radius $r$ is heated up to a temperature $T$ and then allowed to cool. The rate of cooling of shell is proportional to

If an object at absolute temperature $\left(T\right)$ radiates energy at a rate of $R,$ then select correct graph showing the variation of ${\log }_{e}R$ with ${\log }_e\left(T\right).$

Two diagonally opposite corners of a square made of a four thin rods of same material, same dimensions are at temperature $40°\mathrm{C}$ and $10°\mathrm{C}.$ If only heat conduction takes place, then the temperature difference between other two corners will be

Bottom of a lake is at $0°\mathrm{C}$ and atmospheric temperature is $-20°\mathrm{C}.$ If $1 \mathrm{cm}$ ice is formed on the surface in $24 \mathrm{h}$ then, time taken to form next $1 \mathrm{cm}$ ice is

The power received at distance $d$ from a small metallic sphere of radius $r(<<d)$ and at absolute temperature $T$ is $P.$ If temperature is doubled and distance reduced to half of initial value, then the power received at that point will be

Two bodies $A$ and $B$ of equal masses, area and emissivity cooling under Newton's law of cooling from same temperature are represented by the graph. If $\theta$ is the instantaneous temperature of the body and ${\theta }_0$ is the temperature of surroundings, then relationship between their specific heats are

Assume that Solar constant is $1.4 \mathrm{kW} {\mathrm{m}}^{-2},$ radius of sun is $7\times {10}^5 \mathrm{km}$ and the distance of earth from centre of sun is $1.5\times {10}^8 \mathrm{km}.$ Stefan's constant is $5.67\times {10}^{-8} \mathrm{W} {\mathrm{m}}^{-2}{ \mathrm{K}}^{-4},$ find the approximate temperature of sun