QJEEAdv23Pha3db: JEE Advanced 2023 Physics - Class 12 JEEAdv23Pha3db Solution: In a radioactive decay process, the activity is defined as ,…

In a radioactive decay process, the activity is defined as $A=-\frac{d N}{d t}$ , where $N(t)$ is the number of radioactive nuclei at time $t$ . Two radioactive sources, $S_1$ and $S_2$ have same activity at time $t=0$ . At a later time, the activities of $S_1$ and $S_2$ are $A_1$ and $A_2$ , respectively. When $S_1$ and $S_2$ have just completed their $3^{\text {rd }}$ and $7^{\text {th }}$ half-lives, respectively, the ratio $A_1 / A_2$ is _________.