# Heat flux over a surface [closed] I was able to answer the question logically but could not account for the exact values of fraction of the total radiation, so please give some good way to exactly calculate the fraction of the total radiation as detected by detector. Please help.

## closed as off-topic by Jon Custer, Bill N, AccidentalFourierTransform, John Rennie, heatherFeb 11 '17 at 17:52

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – Jon Custer, Bill N, AccidentalFourierTransform, John Rennie, heather
If this question can be reworded to fit the rules in the help center, please edit the question. The source of the radiation is above O. Construct 3 more squares which are identical to $OBCD$ as shown in the diagram. Similarly, construct 6 big squares to form a cube. The source of radiation is at the center of the cube, right above O. So each face of the cube would get $\frac{1}{6}$ of the radiation.
Now go back to the first image. Each face consists of 4 identical squares. The radiation hitting each face is shared equally by each part of the face. Therefore, the square $OBCD$ gets $\frac{\frac{1}{6}}{4}$, i.e: $\frac{1}{24}$ of the total radiation.