How to find any value in logarithmic diagram

0:00 Intro
0:25 Question to help you
1:51 Linear versus log
3:10 Why 50 is in the middle of 1 and 2900
4:09 Why 50 is in the middle of 0.1 and 25400
4:36 Find 3.14
5:35 Try yourself: 31.4 and 628
6:04 Shortcuts (advanced comments)
6:51 Changing log base
8:35 Why depreciate "log"?
Why is 50 in the middle of 1 and 2900? After watching this video, I hope you will be able to explain why and be able to find any value on a logarithmic scale.

[@ThisIsMeEmna]

thank you!! been looking for something useful for so long!

[@mrbtiger4838]

Thank you very much for this, it was clear and easy to understand.

[@MrMido7arakat]

Thanks for the explanation. This is the best approach I have come across explaining how to deal with logarithmic charts.

[@PLE_LU]

Thank you, we're glad that it helped you. We almost exclusively make videos for students taking our courses, but we make some videos publicly available with the hope that others might find them useful.

[@MostafaMASLOUHI]

Thank you so much. I have looking for this and no one talk about this as you did.

[@PLE_LU]

Glad that it helped. My guess is that most mathematicians would dislike this video as I am not mathematically rigorous in the explanation 🙂

[@swordrstr5548]

Great!, Thank you sir -easy to understand _ I am also study chem eng

[@abdallahbukhari4382]

Thank you so much

[@swordrstr5548]

Hi sir I have a question, what if We got a point line on y-axis (log graph) , how do we know how much is that value (not like you have 3.14 than you find its position - i mean we see a point and then how to find that point's value) ?
Thank you very much
Have a good day sir

[@PLE_LU]

In a diagram with log base 10, I would measure the distance between the closet 10^n and 10^(n+1), let's call that distance A, and then the distance between 10^n and our point, let's call that A.
Using the same reasoning as in the video, we get
a/A = (lg x - lg 10^n)/(log10^(n+1) - log10^n
and we can solve for x. So, if a/A=0.93, we get
0.93= (lg x - lg 0.1)/(lg 1- lg 0.1)
lg x = 0.93*(lg 1 - lg 0.1)+ lg 0.1
x= 10^( 0.93*(lg 1 - lg 0.1)+ lg 0.1)=0.85

[@swordrstr5548]

@@PLE_LU great, thank you sir

[@PLE_LU]

@@swordrstr5548 today when adding timestamps to this video I realize I perhaps should have also given the shortcut version hinted in the video section that starts at 6:04: If a/A=0.93 according to the above, then 10^0.93=8.5. The only value between 0.1 and 1 that starts with the digits 8 and 5 is 0.85 and hence that's the answer

[@vitech1990]

i've watched two of your videos and I still cant can't understand what you are doing.

[@PLE_LU]

We almost exclusively make videos for students taking our courses, but we make some videos publicly available with the hope that others might find them useful. We might use feedback from others to help us make videos better, but we do need more constructive, informative feedback than what you have given us. Care to expand a bit on your impressions?

[@macacopaco4664]

very confusing video