Physics - Modern Physics Question with Solution | TestHub

Two different radioactive elements with half-lives ' ${\mathrm{T}}_1$ ' and ' ${\mathrm{T}}_2$ ' have undecayed atoms ' ${\mathrm{N}}_1{}^{\prime }$ and ${}^{\prime }{\mathrm{N}}_2{}^{\prime }$ respectively, present at a given instant. The ratio of their activities at this instant is