The activity of a radioactive substance is 4700 per minute. Five minute later the activity is 2700 per minute. Find
(a) decay constant and
(b) half-life of the radioactive substance.

Explanation

Given : intial activity `A_(0)=lambda N_(0)=4700`
final activity A= `lambda=N=2700`
t=5 min
`N=N_(0)e^(-lambda tau)`
`lambda=(2.303)/(5xx60) log_(10)(4700)/(2700)` `lambda=0.00184 S^(-1)`
`lambda=(0.693)/(T_(1/2))`
`T_(1/2)=(0.693)/(0.00184)`
`T_(1//2)=376.63 sec`
`T_(1//2)=6.2 min`