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10.2 , transmission of heat — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics10.2 , transmission of heat1 Mark
MCQ
Two identical plates of different metals are joined to form a single plate whose thickness is double the thickness of each plate. If the coefficients of conductivity of each plate are $2$ and $3$ respectively, then the conductivity of composite plate will be
  • A
    $5$
  • ✓
    $2.4$
  • C
    $1.5$
  • D
    $1.2$
✓

Answer

Correct option: B.
$2.4$
b
(b)Thermal conductivity of composite plate
${K_{eq}} = \frac{{2{K_1}{K_2}}}{{{K_1} + {K_2}}} = \frac{{2 \times 2 \times 3}}{{2 + 3}}$$ = \frac{{12}}{5}$= $2.4$

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