CUET · PHYSICS · PYQ PAPER 2023
After how many half lives a radioactive substance will decay to 6.25% of its original value :
- A One half life
- B Two half lives
- C Three half lives
- D Four half lives
Answer & Solution
Correct Answer
(D) Four half lives
Step-by-step Solution
Detailed explanation
\(\frac{N}{N_0} = \left(\frac{1}{2}\right)^n\) \(0.0625 = \left(\frac{1}{2}\right)^n\) \(\frac{1}{16} = \left(\frac{1}{2}\right)^n\) \(\left(\frac{1}{2}\right)^4 = \left(\frac{1}{2}\right)^n\) \(n = 4\)
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