A cylindrical rod having temperature $T_1$ and $T_2$ at its end. The rate of flow of heat $Q_1$ cal/sec. If all the linear dimension are doubled keeping temperature constant, then rate of flow of heat $Q_2$ will be
- $4Q_1$
- $2Q_1$
- $\frac{Q_1}{4}$
- $\frac{Q_1}{2}$
The Correct Option is B
Solution and Explanation
When linear dimensions are double.
$A_1 \propto r^2_1, \, L_1 = L$
$A_2 \propto 4r^2_1, \, L_1 = 2L$ so $Q_2 = 2Q_1$.
Top Questions on Thermal Expansion
- A wire of length 0.5 m and area of cross-section $4 \times 10^{-6}$ m$^2$ at a temperature of 100°C is suspended vertically by fixing its upper end to the ceiling. The wire is then cooled to 0°C, but is prevented from contracting, by attaching a mass at the lower end. If the mass of the wire is negligible, then the value of the mass attached to the wire is [Young's modulus of material of the wire = $10^{11}$ N/m$^2$; coefficient of linear expansion of the material of the wire = $10^{-5}$ K$^{-1}$ and acceleration due to gravity = 10 m/s$^2$]
- AP EAPCET - 2025
- Physics
- Thermal Expansion
- The apparent coefficient of expansion of a liquid, when heated in a copper vessel, is \( C \) and when heated in a silver vessel is \( S \). If \( A \) is the linear coefficient of expansion of copper, then the linear coefficient of expansion of silver is:
- WBJEE - 2025
- Physics
- Thermal Expansion
- If the resistance of a wire is 5 $ \Omega $ and 6 $ \Omega $ at 30°C and 40°C respectively, find the temperature coefficient of resistance.
- KEAM - 2025
- Physics
- Thermal Expansion
- The wavelength of body radiation having maximum energy is $ \lambda_m $ at temperature $ T $. If the wavelength of radiation corresponds to maximum energy is $ \frac{\lambda}{3} $, then temperature is:
- KEAM - 2025
- Physics
- Thermal Expansion
- Consider a rectangular sheet of solid material of length $ \ell = 9 $ cm and width $ d = 4 $ cm. The coefficient of linear expansion is $ \alpha = 3.1 \times 10^{-5} $ K$^{-1}$ at room temperature and one atmospheric pressure. The mass of the sheet is $ m = 0.1 $ kg and the specific heat capacity $ C_v = 900 $ J kg$^{-1}$K$^{-1}$. If the amount of heat supplied to the material is $ 8.1 \times 10^2 $ J, then the change in area of the rectangular sheet is:
- JEE Main - 2025
- Physics
- Thermal Expansion
Questions Asked in JEE Advanced exam
- Let $ x_0 $ be the real number such that $ e^{x_0} + x_0 = 0 $. For a given real number $ \alpha $, define $$ g(x) = \frac{3xe^x + 3x - \alpha e^x - \alpha x}{3(e^x + 1)} $$ for all real numbers $ x $. Then which one of the following statements is TRUE?
- JEE Advanced - 2025
- Fundamental Theorem of Calculus
- At 25$^\circ$C, the concentration of H$^+$ ions in $ 1.00 \times 10^{-3} \, \text{M} $ aqueous solution of a weak monobasic acid having acid dissociation constant $ K_a = 4.00 \times 10^{-11} $ is $ X \times 10^{-7} \, \text{M} $. The value of $ X $ is ____. {Use: Ionic product of water $ K_w = 1.00 \times 10^{-14} $ at 25$^\circ$C
- JEE Advanced - 2025
- Ionic Equilibrium
- Consider the vectors $$ \vec{x} = \hat{i} + 2\hat{j} + 3\hat{k},\quad \vec{y} = 2\hat{i} + 3\hat{j} + \hat{k},\quad \vec{z} = 3\hat{i} + \hat{j} + 2\hat{k}. $$ For two distinct positive real numbers $ \alpha $ and $ \beta $, define $$ \vec{X} = \alpha \vec{x} + \beta \vec{y} - \vec{z},\quad \vec{Y} = \alpha \vec{y} + \beta \vec{z} - \vec{x},\quad \vec{Z} = \alpha \vec{z} + \beta \vec{x} - \vec{y}. $$ If the vectors $ \vec{X}, \vec{Y}, \vec{Z} $ lie in a plane, then the value of $ \alpha + \beta - 3 $ is ________.
Two identical concave mirrors each of focal length $ f $ are facing each other as shown. A glass slab of thickness $ t $ and refractive index $ n_0 $ is placed equidistant from both mirrors on the principal axis. A monochromatic point source $ S $ is placed at the center of the slab. For the image to be formed on $ S $ itself, which of the following distances between the two mirrors is/are correct:
- JEE Advanced - 2025
- Ray optics and optical instruments
- Let $$ \alpha = \frac{1}{\sin 60^\circ \sin 61^\circ} + \frac{1}{\sin 62^\circ \sin 63^\circ} + \cdots + \frac{1}{\sin 118^\circ \sin 119^\circ}. $$ Then the value of $$ \left( \frac{\csc 1^\circ}{\alpha} \right)^2 $$ is \rule{1cm}{0.15mm}.
- JEE Advanced - 2025
- Some Applications of Trigonometry
JEE Advanced Notification
Concepts Used:
Thermal Expansion
Thermal expansion is the tendency of matter to change its shape, area, and volume in response to a change in temperature. Temperature is a monotonic function of the average molecular kinetic energy of a substance.
The expansion of the solid material is taken to be the linear expansion coefficient, as the expansion takes place in terms of height, thickness and length. The gaseous and liquid expansion takes the volume expansion coefficient. Normally, if the material is fluid, we can explain the changes in terms of volume change.
The bonding force among the molecules and atoms differs from material to material. These characteristics of the compounds and elements are known as the expansion coefficient.
