Chapter 19, Problem 48A

Interpretation Introduction

Interpretation: Relative abilities to penetrate have to be described for $\text{α,β}\text{and}\text{γ}$ radiations.

Concept introduction: Nuclear reactions are those where an unstable nuclide disintegrates in order to form a stable nuclide with emission of various radiations feasibly. It is called radioactivity of nucleus. The particles or rays emitted during the process are alpha, beta and gamma rays which cause a change in the identity of nucleus.

Beta particle is one that has unit negative charge and alpha particle is one that has 2 unit positive charges and is equivalent to helium atom ${}_2^4\text{He}$ .

Answer to Problem 48A

Most penetrating is $\text{γ}$ ray and least is $\text{α}$ . $\text{β}$ ray penetrates up to 1 cm into the human body.

Explanation of Solution

When radioactive substance disintegrates, three types of radiations are produced : $\text{α}$ , $\text{β}$ and $\text{γ}$ radiations. All three affect on the basis of their ability to penetrate into human body. Most penetrating is $\text{γ}$ ray and least is $\text{α}$ . $\text{α}$ rays can be obstructed by paper or metal foil simply because their speed is less due to its heavy mass of 4 units, equivalent to that of ${}_2^4\text{He}$ . $\text{β}$ ray can penetrates up to 1 cm into the human body.

Conclusion

Most penetrating is $\text{γ}$ ray and least is $\text{α}$ . $\text{β}$ ray penetrates up to 1 cm into the human body.