Peoples Physics Concepts

http://www.ck12.org Chapter 20. Radioactivity and Nuclear Physics

20.2 Half Life

• Explain what is meant by half life.


• Solve problems involving radioactive decay.

Students will learn what is meant by half life and how to solve problems involving radioactive decay.

Key Equations

M=M 0 (

1

2

)

tt

H

The amount of massMof the substance surviving after an originalM 0 nuclei decay for timetwith a half-life oftH.

t=tH

lnMM 0

ln^12

The amount of timetit takes a set of nuclei to decay to a specified amount.

N=N 0 ex p−λt

The numberNof nuclei surviving after an originalN 0 nuclei decay for timetwith a half-life oftH.