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Thermodynamics

# Two identical rods A and B when joined in series conduct heat at a rate of 4 w at steady state . If they are connected in parallel , they conduct heat at rate of

$(a)\;1\;W\qquad(b)\;16\;W\qquad(c)\;8\;W\qquad(d)\;4\;W$

Answer : $\;16\;W$
Explanation :
In series $\;Q_{1}=\large\frac{KA(T_{1}-T_{2})}{2L}$
In parallel
$Q_{2}=\large\frac{2KA(T_{1}-T_{2})}{L}$
$=4(\large\frac{KA(T_{1}-T_{2})}{2L})$
$Q_{2}= 4Q_{1}= 16 W$