Question

Using the equation (N(t) = N0 e^−λt) Calculate the amount left of a radioactive sample amount N0 if the decay constant is 0.00125 seconds and the time is 180 seconds? (Hint: Your answer will not be a number. Instead, it will be a decimal or percent of the variable N0)

Answer 1

The equation is

$\\ \rm\Rrightarrow N(t)=N_o(e^{-\lambda t})$

Put values

$\\ \rm\Rrightarrow N(180)$

$\\ \rm\Rrightarrow N_o(e^{-0.00125(180)}$

$\\ \rm\Rrightarrow N_o(e^{-0.225})$

$\\ \rm\Rrightarrow 0.798N_o$

Or

• 79.8% of N_o