Heat is flowing through a conductor of length l from x = 0 to x = l . If its thermal resistance per

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10-2.Transmission of Heat

medium

Heat is flowing through a conductor of length l from $x = 0$ to $x = l$ . If its thermal resistance per unit length is uniform, which of the following graphs is correct

Solution

(c) $\frac{{dQ}}{{dt}} = – KA\frac{{d\theta }}{{dx}}$
( $\frac{{dQ}}{{dt}},$ $K$ and $A$ are constants for all points
$ \Rightarrow \,\,d\theta \propto – dx$; i.e. temperature will decrease linearly with $x$ .

Standard 11

Physics

Two identical beakers $A$ and $B$ contain equal volumes of two different liquids at $60\,^oC$ each and left to cool down. Liquid in $A$ has density of $8 \times10^2\, kg / m^3$ and specific heat of $2000\, Jkg^{-1}\,K^{-1}$ while liquid in $B$ has density of $10^3\,kgm^{-3}$ and specific heat of $4000\,JKg^{-1}\,K^{-1}$ . Which of the following best describes their temperature versus time graph schematically? (assume the emissivity of both the beakers to be the same)

hard

(JEE MAIN-2019)

Newton’s law of cooling, holds good only if the temperature difference between the body and the surroundings is

easy

If a liquid takes $30 \;sec$ in cooling from $80^{\circ} C$ to $70^{\circ} C$ and $70 \;sec$ in cooling from $60^{\circ} C$ to $50^{\circ} C$, then find the room temperature.

medium

Liquid is filled in a vessel which is kept in a room with temperature ${20^o}C$. When the temperature of the liquid is ${80^o}C$, then it loses heat at the rate of $60\;cal/\sec $. What will be the rate of loss of heat when the temperature of the liquid is ${40^o}C$ ……. $cal/\sec $

medium

An object kept in a large room having air temperature of $25^{\circ} \mathrm{C}$ takes $12$ minutes to cool from $80^{\circ} \mathrm{C}$ to $70^{\circ} \mathrm{C}$. The time taken to cool for the same object from $70^{\circ} \mathrm{C}$ to $60^{\circ} \mathrm{C}$ would be nearly…..$min$

medium

(NEET-2019)

Heat is flowing through a conductor of length l from $x = 0$ to $x = l$ . If its thermal resistance per unit length is uniform, which of the following graphs is correct

Solution

Similar Questions

Newton’s law of cooling, holds good only if the temperature difference between the body and the surroundings is

If a liquid takes $30 \;sec$ in cooling from $80^{\circ} C$ to $70^{\circ} C$ and $70 \;sec$ in cooling from $60^{\circ} C$ to $50^{\circ} C$, then find the room temperature.

Liquid is filled in a vessel which is kept in a room with temperature ${20^o}C$. When the temperature of the liquid is ${80^o}C$, then it loses heat at the rate of $60\;cal/\sec $. What will be the rate of loss of heat when the temperature of the liquid is ${40^o}C$ ……. $cal/\sec $

An object kept in a large room having air temperature of $25^{\circ} \mathrm{C}$ takes $12$ minutes to cool from $80^{\circ} \mathrm{C}$ to $70^{\circ} \mathrm{C}$. The time taken to cool for the same object from $70^{\circ} \mathrm{C}$ to $60^{\circ} \mathrm{C}$ would be nearly…..$min$

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