What do logarithms mean in layman's terms?

Quora: What do logarithms mean in layman's terms?
 
Great answers already. I'll try to make this one much more simpler with no graphs and less numbers.

Before I explain logarithms, I'll give you an insight on one of the application areas where logs are used.

This is an image of the tragic earthquake that devastated much of Nepal in 2015.  It occurred with a magnitude of 8 on the Richter scale.

Seismologists say an earthquake with a magnitude  2 is equivalent to 1 Ton of TNT explosion.

In this case, we have magnitude 8 on the scale. So, what do you think the equivalent number of TNT explosives would be?

If you thought the answer is 4 Tons, then you're wrong. Interestingly, a magnitude 8 earth quake is equivalent to a detonation of 1 Billion Tons of TNT.

Now, if you wonder how did I get to this number (1 Billion), it is because Richter is a logarithmic scale.


Explanation

We know, 10-8 = 2. similarly the inverse is, 8+2=10.
likewise, 10/2 = 5 and 5*2=10.

So we got inverses for all four operations.

Now, take the example of 10^3 = 10*10*10 = 1000. What is the inverse of this operation(exponentiation) ?

Do we have any way to put this the other way around?
Yes, that's the idea behind logarithms.

3 = log(10) 1000, if you now look in the log book for the number 1000, you should see 3.

In mathematics, the logarithm is the inverse operation to exponentiation.

The above example uses log with the base 10.

Here's another example with log base 5,
5^3 = 5*5*5 = 125 and the log equivalent for  log(5) 125 = 3.

Going back to our discussion about earthquakes, when I said an earthquake with a magnitude  2 is equivalent to 1 Ton of TNT explosion,  the calculation goes like this, 10^2=100=1Ton.

similarly, with a magnitude 8, 10^8 = 1 Billion Tons.

Hope this answers your question.

Carrots, Eye Sight and WW2: Myth and the Fact

Carrots improve eye sight..


Growing up as a kid, I've been told this multiple times and still it is a common belief people have. But is there any correlation between carrots and eye sight?  Of course, carrots provide all necessary vitamins needed for eyes but they really don't improve eye sight.

The story behind this most popular myth goes back to the days of world war 2 where couple of developments happened in Britain.

1. Carrots were locally produced in Britain and it was the only crop that can be produced in abundance with less effort, thanks to Europe's weather round the year. Due to naval blockade set by the Germans, Britain found it difficult to import food from her colonies and British economists predicted a major food shortage is imminent. Since Carrots were produced domestically, they wanted a way  to encourage people to eat carrots.                                                 
2. During the war, British RAF had developed an advanced radar tech that can detect aircraft flybys even in the dark. RAF were then reeling with the problem of sudden surge in identification and hit rates of German aircrafts, especially during night time. Also, with the help from Poles, British now knew to decode enigma which, at that time was considered the greatest breakthrough. But they had to keep this a secret for obvious reasons. Though they knew every German fleet movement and their secret communications, they still had to let Germans take down their targets and give up on the resources to avoid suspicion among Germans.

So, how to use these two tech breakthroughs without causing suspicion? They decided to hit 2 birds with one stone; through massive propaganda that carrots improve eye sight. This way, they convinced the pilots to consume more carrots which happened to explain the reason behind increased hit rate of German aircrafts in the night.

Pilots were supposedly asked to keep munching away carrots which improved their eye sight in dark to extreme levels. Apparently Germans and the whole world took the bait and believed it. And a lot of people continue doing it till date.

Filmy jazz tune of the 1960's era

A simple filmy jazz tune of the 1960's era.
Composed by: Naren, Kailaash
Year: 2009

Adi Neethan Enthan Kadhal

A rough track I had sung for a short film.
Music: Vetri
Vocals: Kailaash
Year: 2010