# Half Life Calculator, Formula, Calculation, Example

### Half Life Calculator Formula

Half-life defines the time it takes for a substance undergoing a decay process to decrease by half. It describes the quantities encountered in exponential decay where the half-life is constant over the entire period of decay. The half-life can be determined for exponential decay processes, although the half-life is quite different in the decay process.

Half Life Calculator Formula is given by,

Remaining quantity  N(t)  is equal to the product of the initial quantity  N0  half life t1/2 . Hence life calculator formula has been written as,

N(t) = N0 (1/2)t/t1/2

Where,

N(t) is the remaining quantity

N is the initial quantity

t1/2 is the half life

N(t) = N eλt

t ½ =  loge2 / λ

Where,

λ is the decay constant

t is the time period

### Example 1:

The decay constant of a substance is 0.71 s-1.find the half life of the substance.

### Solution :

decay constant λ =0.71

t ½ =  loge2 / λ

t ½  = 0.693 / λ

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t ½  =0.693 / 0.71

t ½ = 0.976 s.

### Example 2:

Find the value of the decay constant of a radioactive substance having a half – life of 0.05 seconds.

### Solution :

t ½  = 0.05

λ =  loge2 / t ½

t ½  = 0.693 / 0.05

t ½  = 13.86.