Project ForgeHeat Transfer
Convection & Radiation
GATE 2021
Medium
An infinitely long pin fin attached to an isothermal hot surface transfers heat at a steady rate Q̇₁ to ambient air. If the thermal conductivity of the fin material is doubled (all else constant), the heat rate becomes Q̇₂. The ratio Q̇₂/Q̇₁ is
- √2
- B2
- C1/√2
- D1/2
Explanation
For an infinitely long fin, Q̇=√(hPkA)×θb. Q̇ ∝ √k, so doubling k gives Q̇2/Q̇1=√(2k/k)=√2.
Source: GATE ME 2021 Session 1 (ME-1) (2021)
This question is part of a 15-day revision cycle — sign in and Project Forge will bring it back the day before you'd forget it.