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Friday, 9 October

JEE Main 2022 · PhysicsNumerical answerNumerical valueEasyCalculation

JEE Main 29 June 2022, Shift 1, Physics Q53

Question 53 of 90 in this shift, Physics question 23 of 30, Section B.

As per the given figure, two plates A and B of thermal conductivity K and 2 K are joined together to form a compound plate. The thickness of plates are 4.0 cm and 2.5 cm respectively and the area of cross-section is 120 cm2\mathrm{cm^2} for each plate. The equivalent thermal conductivity of the compound plate is (1+5α)\left(1 + \frac{5}{\alpha}\right)K, then the value of α\alpha will be ____________.

The figure, in words

Two plates joined side by side: plate A (thermal conductivity K, thickness 4.0 cm) at 100 C on the left, plate B (conductivity 2K, thickness 2.5 cm) at 0 C on the right.

Official answer

21

NTA final key (2022 Session 1).

Chapter
Thermal Properties of Matter
Topic
Heat Conduction
Idea tested
Equivalent Thermal Conductivity (Series)

Same topic in other shifts

All Heat Conduction questions
  1. 7 Apr 2025, Shift 2 · Q47Two cylindrical rods A and B made of different materials, are joined in a straight line. The ratios of lengths, radii and thermal…MediumNumerical value
  2. 13 Apr 2023, Shift 2 · Q53Two plates A and B have thermal conductivities 84 Wm−1K−184\ \mathrm{Wm^{-1}K^{-1}} and 126 Wm−1K−1126\ \mathrm{Wm^{-1}K^{-1}} respectively. They have same…EasyNumerical value
  3. 24 Jun 2022, Shift 1 · Q50Two metallic blocks M1M_1 and M2M_2 of same area of cross-section are connected to each other (as shown in figure). If the thermal…MediumSingle correctHas a figure
  4. 6 Sep 2020, Shift 2 · Q8Three rods of identical cross-section and lengths are made of three different materials of thermal conductivity K1K_1, K2K_2 and K3K_3,…MediumSingle correctHas a figure

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.