The walls of a closed cubical box of edge `50cm` are made of a material of thickness
Channel: Doubtnut
Date: 2020-08-16

The walls of a closed cubical box of edge `50cm` are made of a material of thickness `1mm` and thermal conductivity `4xx10^(-4) cm^(-1)(.^@C)^(-1)`. The interior of the box is maintained `100^(@)C` above the outside temperature by a heater placed inside the box and connected across `420V` d.c. calculate the resistance of copper.