One face of a copper cube of edge 10 cm is maintained at `100^(@)C` and the opposite face is maintained at `0^(@)C`. All other surfaces are covered with an insulating material. Find the amount of heat flowing per second through the cube. Thermal conductivity of copper is `385Wm^(-1) C^(-1)`.

Explanation

Heat will flow from the end at `100^(@)C` to the end at `0^(@)C`.
Area of cross-section perpendicular to direction of heat flow.
`A - 4m^(2)`
then `(Q)/(t) = KA ((T_(H)-T_(C)))/(L)`
`Q = ((200W//m^(@)C)(4m^(2))(100^(@)C-0^(@)C)(5sec))/(2m) =209 kJ`