Radiation

Step 1: Concept
According to Stefan-Boltzmann Law, .
Step 2: Analysis
New temperature . New radiation . Increase .
Step 3: Conclusion
The percentage increase is approximately 400%.
Final Answer: (D)

Step 1: Total Subsets
Total subsets of a set with 9 elements = .
Step 2: Subsets with NO Odd Numbers
Odd numbers: (5 numbers). Even numbers: (4 numbers).
Subsets containing only even numbers = .
Step 3: Calculation
Required subsets = Total subsets - Subsets with only even numbers.
.
Final Answer: (c)

Concept: Stefan–Boltzmann law: where is energy radiated per unit area per unit time (i.e., power per unit area).

Step 1: Dimensions of .


Step 2: Dimensions of .