Three conducting rods of same material and cross-section are shown in figure. Temperatures of A, D a

English

Gujarati

Hindi

10-2.Transmission of Heat

medium

Three conducting rods of same material and cross-section are shown in figure. Temperatures of$ A, D$ and $C$ are maintained at $20^o C, 90^o C$ and $0^o C$. The ratio of lengths of $BD$ and $BC$ if there is no heat flow in $AB$ is:

A

$2 / 7$

B

$7 / 2$

C

$9 / 2$

D

$2 / 9$

Solution

since there is no flow of heat in rod, so temperature of $B$ is equal to temperature at $A$

i.e.,

$\theta_{B}=\theta_{A}=20^{\circ} C$

Heat flowing through $D B$ per second $=$ heat flowing through

i.e., $\frac{K A\left(90^{\circ}-20^{\circ}\right)}{I_{B D}}=\frac{K A\left(20^{\circ}-0^{\circ}\right)}{I_{B C}}$

$\therefore \frac{I_{B C}}{I_{B D}}=\frac{2}{7}$

Standard 11

Physics

Share

Similar Questions

A brass boiler has a base area of $0.15\; m ^{2}$ and thickness $1.0\; cm .$ It boils water at the rate of $6.0\; kg / min$ when placed on a gas stove. Estimate the temperature (in $^oC$) of the part of the flame in contact with the boiler. Thermal conductivity of brass $=109 \;J s ^{-1} m ^{-1} K ^{-1} ;$ Heat of vaporisation of water $=2256 \times 10^{3}\; J kg ^{-1}$

medium

The lengths and radii of two rods made of same material are in the ratios $1 : 2$ and $2 : 3$ respectively. If the temperature difference between the ends for the two rods be the same, then in the steady state, the amount of heat flowing per second through them will be in the ratio

medium

Surface of the lake is at $2^{\circ} C$. The temperature of the bottom of the lake is ……. $^{\circ} C$

easy

The rate of heat flow through the cross-section of the rod shown in figure is ($T_2 > T_1$ and thermal conductivity of the material of the rod is $K$)

hard

Two identical square rods of metal are welded end to end as shown in figure $(a)$. Assume that $10\, cal$ of heat flows through the rods in $2\, min$. Now the rods are welded as shown in figure, $(b)$. The time it would take for $10$ cal to flow through the rods now, is …….. $\min$

medium