Two vessels of different materials are similar in size in every respect. The same quantity of ice filled in them gets melted in $20$ minutes and $30$ minutes. The ratio of their thermal conductivities will be
Medium
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(a) $Q = \frac{{KA({\theta _1} - {\theta _2})t}}{l};$ in both the cases , $A$ , $l$ and $({\theta _1} - {\theta _2})$ are same so $Kt =$ constant
==>$\frac{{{K_1}}}{{{K_2}}} = \frac{{{t_1}}}{{{t_2}}} = \frac{{30}}{{20}} = \frac{3}{2}$= $1.5.$
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