Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Physics
Chapter
Thermal Properties of Matter

NTA Abhyas 2020 · Physics · Thermal Properties of Matter

Four rods, of different radii r and length l , are used to connect...

Four rods, of different radii rr and length ll, are used to connect two reservoirs of heat at different temperatures. The rod that will conduct the heat fastest will be

Options

  1. Ar=2cm,l=0.5mr = 2cm, l = \text{0.5}m
  2. Br=1cm,l=0.5mr = 1cm, l = \text{0.5}m
  3. Cr=2cm,l=2mr = 2cm, l = \text{2}m
  4. Dr=1cm,l=1mr = 1cm, l = \text{1}m

Correct answer

A. r=2cm,l=0.5mr = 2cm, l = \text{0.5}m

Step-by-step solution

∆T∆t=KA(∆T∆x)=K(\pir2)∆T(l)\dfrac{∆ T}{∆ t} = KA\left(\dfrac{∆ T}{∆ x}\right) = K\left(\pir^{2}\right)\dfrac{∆ T}{\left(l\right)}

∴(∆Q∆t)∝r2l∴ \left(\dfrac{∆ Q}{∆ t}\right) ∝ \dfrac{r^{2}}{l}, which is maximum in this case.
Practice Thermal Properties of Matter on Quantrex Academy →

More from Thermal Properties of Matter

As shown in the figure, an insulated container is fitted with a thermally conducting but… JEE Advanced 2026The heat extracted out of x gram of water initially at 50°C to cool it down to 0°C is… JEE Main 2026The temperature of a metal strip having coefficient of linear expansion α is increased… JEE Main 2026Which of the following best represents the temperature versus heat supplied graph for… JEE Main 202610 kg of ice at -10^ ∘ C is added to 100 kg of water to lower its temperature from 25 ^ ∘… JEE Main 2026A brass wire of length 2 m and radius 1 mm at 27^ ∘ C is held taut between two rigid… JEE Main 2026Rods x and y of equal dimensions but of different materials are joined as shown in… JEE Main 2026An aluminium and steel rods having same lengths and cross-sections are joined to make… JEE Main 2026 Full Thermal Properties of Matter list All NTA Abhyas JEE Main PYQs