\(=7\,cals/(cm^2s)\)
Let rate of heat radiated at \((727+273)\,K=x\,cals/(cm^2s)\)
By \(Stefan's\,law,\,7\propto(500)^4\,and\,x\propto(1000)^4\)
\(\therefore \frac{x}{7} = {2^4} \Rightarrow x = 7 \times {2^4} = 112\,cals/\left( {c{m^2}s} \right).\)
કારણ : ટ્યુબલાઇટમાં પ્રકાશનું ઉત્સર્જન ખૂબ ઊંચા તાપમાને થાય છે.