In a radioactive material the activity at time `t_(1)` is `R_(1)` and at a later time `t_(2)`, it is `R_(2)`. If the decay constant of the material is `lambda`, then

Options

A. `R_1 = R_2`
B. `R_1 = R_2e^(-lambda(t_1-t_2))`
C. `R_1 = R_2e^(lambda(t_1-t_2))`
D. `R_1 = R_2(t_2//t_1)`

Answer

B