Chapter 24, Problem 78A

Interpretation Introduction

Interpretation:

The intensity at distance of 3.5m needs to be determined.

Concept introduction:

Radiation is the emission of energy through space in the form of particles.

Answer to Problem 78A

Intensity of radiation( ${\text{I}}_{\text{2}}$ ) from a distance of 3.5m is $0.28{\text{mrem/ms}}^{\text{2}}$.

Explanation of Solution

Given information,

$\begin{array}{l}{\text{I}}_1=\text{0}{\text{.85mrem/ms}}^{\text{2}}\\ {\text{d}}_{\text{1}}=\text{2m}\\ {\text{d}}_2=3.\text{5m}\end{array}$

Relation between radiation intensity and distance is

$\begin{array}{l}{\text{I}}_{\text{1}}{\text{d}}_{\text{1}}{}^{\text{2}}={\text{I}}_{\text{2}}{\text{d}}_{\text{2}}{}^{\text{2}}\\ {\text{I}}_{\text{2}}=\frac{{\text{I}}_{\text{1}}{\text{d}}_{\text{1}}{}^{\text{2}}}{{\text{d}}_{\text{2}}{}^{\text{2}}}\\ {\text{I}}_{\text{2}}=\frac{0.85\times {(2)}^2}{{(3.5)}^2}\\ {\text{I}}_{\text{2}}=0.28{\text{mrem/ms}}^{\text{2}}\end{array}$

Conclusion

The distance from the source determinesintensity of radiation. That is I is directly proportional to d.