Physics - Nuclear Physics (22 of 22) Find the Age of a Moon Rock

[@mdriyadhossensajjad]

Completed!! Not only this but many of your playlists from Bangladesh. Thanks sir, your lectures are really understandable.

[@MichelvanBiezen]

You are most welcome. Glad you found our videos. Welcome to the channel! 🙂

[@mdriyadhossensajjad]

@@MichelvanBiezen Thanks. Sir! Can you make a playlist on Astrophysics. I know you have one. But I want some different like only math and theory based. Like I've learned from "Astronomy Principles and Practices and An introduction to modern Astrophysics books". I mean to say Astronomy and Astrophysics that has a level of IOAA and IAO.

[@farukuzogirmabello3679]

Your lecture series is extraordinary excellent, thanks you so much sir from Nigeria

[@MichelvanBiezen]

Thank you and welcome to the channel!

[@Birthdragon]

Dear DR Good day I have a request can you upload videos about applications or the generators about the nuclear ( just explain ) And thanks

[@KeremBostan]

Thank you sir! It was a seminal playlist.

[@shefyjohnson5464]

Sir, how do we solve this ---- if a iodine-131 sample gives 85 count per second what will be the rate at the end of 10 days? Kindly help. Thank you.

[@MichelvanBiezen]

You need to know the half life of Iodine-131. When you look it up, you find that it is 8.02 days. Then you have to find the decay constant: lambda = - ln(0.5) / T(1/2) = 0.693/8.02 = 0.98643 Then N = 85 e^(0.98643 t) where t = 10 days = 85 x 0.42136 = 35.8

[@shefyjohnson5464]

@@MichelvanBiezen Thank you so much Sir!!⭐️⭐️

[@shefyjohnson5464]

Sir, for the question - if a sample of iodine-131 gives 220 counts per second as clock starts and later gives 55 counts per second, how much time has lapsed? I got the answer as 15 , because I used lambda = 0.693/8.02 days. So is the value of t that I calculated 15 seconds or 15 days? Do we need to take the values of lambda and t in same units? Like per second or per day? Or is lambda independent of unit of t value? Also do the initial and final values of N and No which are in counts per second affect the units for lambda and t?

[@MichelvanBiezen]

The value of lambda is given for a specific time interval (seconds, minutes, hours, days, years, etc.) depending on how the half life is expressed. So in this case we were using days for the half-life and lamda will be relative to days. 220 counts is just the decay rate for the sample. Note that if the sample was twice as big, it would be 440 counts starting out, but lambda would still be the same number.

[@karhukivi]

@@shefyjohnson5464 A bit late, I know, and you probably have the answer by now. Yes, lambda has to be in the same units as t. However, 55 seconds is a quarter of the initial 220, so two half-lives have elapsed, i.e. 16 days, and no calculator required!