Inverse square Law

Question 1

Define the intensity of radiation

Answer 1

The intensity of a beam of electromagnetic radiation at a given point is the total energy per second flowing past the point when normalized to a unit area

Question 2

State the inverse square law

Answer 2

The intensity of the radiation emitted from a small isotropic source is proportional to the inverse square of the distance from that source, provided that there is negligible absorption or scattering of the radiation by
the medium through which it passes

Question 3

Under what conditions is the inverse square law true.

Answer 3

• When radiation is from a Small isotropic source
• When there is no absorption of radiation
• When there is No scattering of radiation

NOT TRUE FOR AN X-RAY BEAM

Question 4

Why does the ISL fail to apply to x-rays.

Answer 4

• X-rays are not emitted from a true point source
• They are not emitted equally in all directions
• Absorption and scattering of the x-rays occurs in the air through which the beam passes

Question 5

Mathematical expression for the ISL

Answer 5

Iα1/d2
I = k/d2

Question 6

isotropic source

Answer 6

• A theoretical point source of radiation that emits radiation uniformly in all direction.