The ratio of thermal conductivity of two rods of different material is 5 : 4. The two rods of same area of cross-section and same thermal resistance will have the lengths in the ratio :
- 4:05
- 9:01
- 1:09
- 5:04
The Correct Option is D
Solution and Explanation
Top Questions on Heat Transfer
One mole of an ideal gas at 300 K is compressed isothermally from a volume of \(V_1\) to \(V_2\). Calculate:
The work done on the gas
The change in internal energy
The heat exchanged with the surroundings
Use \(R = 8.314\, \text{J/molK}\), \( \ln(2.5) = 0.916\)- AP EAPCET - 2025
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Three conductors of same length having thermal conductivity \(k_1\), \(k_2\), and \(k_3\) are connected as shown in figure. Area of cross sections of 1st and 2nd conductor are same and for 3rd conductor it is double of the 1st conductor. The temperatures are given in the figure. In steady state condition, the value of θ is ________ °C. (Given: \(k_1\) = 60 Js⁻¹m⁻¹K⁻¹,\(k_2\) = 120 Js⁻¹m⁻¹K⁻¹, \(k_3\) = 135 Js⁻¹m⁻¹K⁻¹)
- JEE Main - 2025
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- Two spherical bodies of same materials having radii 0.2 m and 0.8 m are placed in same atmosphere. The temperature of the smaller body is 800 K and temperature of bigger body is 400 K. If the energy radiate from the smaller body is E, the energy radiated from the bigger body is (assume, effect of the surrounding to be negligible):
- JEE Main - 2025
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- Two cylindrical rods A and B made of different materials, are joined in a straight line. The ratio of lengths, radii and thermal conductivities of these rods are : $ \frac{L_A}{L_B} = \frac{1}{2} $, $ \frac{r_A}{r_B} = 2 $, and $ \frac{K_A}{K_B} = \frac{1}{2} $. The free ends of rods A and B are maintained at $ 400 \, K $, $ 200 \, K $, respectively. The temperature of rods interface is ____ K, when equilibrium is established.
- JEE Main - 2025
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- A wire of length 10 cm and diameter 0.5 mm is used in a bulb. The temperature of the wire is 1727°C and power radiated by the wire is 94.2 W. Its emissivity is $ \frac{x}{8} $, where $ x = \ldots $
- JEE Main - 2025
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Concepts Used:
Heat Transfer
What is Heat Transfer?
It is defined as the movement of heat across the border of the system due to a difference in temperature between system and its surroundings.
How is Heat Transferred?
Heat can travel from one place to another in several ways. The different modes of heat transfer include:
- Conduction - Heat flows from things with higher temp to objects with lower temp.
- Convection - Movement of liquid molecules from higher temp regions to lower temp regions.
- Radiation - Radiant heat is present in every other way in our daily lives. Thermal radiations are also known to as radiant heat. Thermal radiation is generated by the emission of electromagnetic waves.
