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Relationship between radiation flux and distance

sabre2th1

I know that:

F = L/(4πd²)

However, I have no clue on how to answer the above question..

Reply 1

Stonebridge

If flux is inversely proportional to d squared then if you double d by how much is F reduced?
Which graph shows this?

Reply 2

sabre2th1

Original post by Stonebridge

If flux is inversely proportional to d squared then if you double d by how much is F reduced?
Which graph shows this?

I always get confused when doubling/halving with inverse-square laws, could you perhaps show me this mathematically?

F proportional to 1/d²

How do I proceed from here?

Thanks a lot

Reply 3

Stonebridge

Inverse square laws are important in physics. You also see it in gravitation and electric fields with the 1/r² laws.
With any inverse square rule if you double the distance the quantity is 4 times less. 4 is 2 squared. If the distance is multiplied by 3 the quantity is 9 times less and so on.
Which graph shows this happening. You are looking to see F becoming 4 times less (a quarter of its value) when you double d.