We know that radioactive element decays with time. The decay law calculates the number of undecayed nuclei in a given radioactive substance.The **decay formula** is given by

Where**,**

N_{o} = Initial amount of radioactive substance,

**$\lambda$** = decay constant

**t **= time taken

**N**_{t} = Amount of radioactive substance present after time t.

Decay constant**($\lambda$)** gives the ratio of number of radioactive atoms decayed to the initial number of atoms. It is given as

N

Decay constant

Decay Law is used to find the decay rate of the given radioactive substance if the above quantities are known.

Related Calculators | |

calculate radioactive decay | half life decay calculator |

Acceleration Formula Calculator | Area of a Circle Formula Calculator |

Problems based on decay are mentioned below.

Given: Initial no of radioactive elements N

Half life t

Time taken t = 30 min,

Decay Constant is given by

$\lambda$ = $\frac{0.693}{t_{\frac{1}{2}}}$

= $\frac{0.693}{20 min}$

= 0.03465

The Decay rate is given by

N

= 1000 $\times$ 0.3536 = 353.63 gms.

353.63 gms of atoms will be present after 30 min.

Initial no of atoms N

Half life period t

Time taken t = 60 min

The decay constant is $\lambda$ = $\frac{0.693}{t_{\frac{1}{2}}}$

= $\frac{0.693}{30 min}$

= 0.0231

The decay rate is given by

N

= 500 $\times$ 0.25

= 125.04 gm.