The activity of a radioactive material is 2.56 × 10–3 Ci. If the half life of the material is 5 days, after how many days the activity will become 2 × 10–5 Ci?
- 30 days
- 35 days
- 40 days
- 25 days
The Correct Option is B
Solution and Explanation
The correct option is( B): 35 days.
\(A=A_{0}e^{-λt}\)
⇒ 2 × 10–5 = 2.56 × 10–3e–λt
\(⇒e^{-λt}=\frac{1}{128}=[\frac{1}{2}]^7\)
\(⇒t=7t_{\frac{1}{2}}=35\,days\)
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Concepts Used:
Speed and Velocity
The rate at which an object covers a certain distance is commonly known as speed.
The rate at which an object changes position in a certain direction is called velocity.
Difference Between Speed and Velocity:
Read More: Difference Between Speed and Velocity