Saturday, August 6, 2011

Doppler(2) effect

Almost every time I try to listen to a lecture (especially those pertaining to a different subject ex EDC, math etc) one thought never fails to pop up. Why am I doing this? How is listening to this stupid lecture gonna help me in anyway? Why is the education system stupid? Why does it make me read shit tht I wld never ever use in my entire life? Well the idea is to make our knowledge “round”. At least thts wht I think it is. I don’t know much abt round knowledge but I certainly believe tht it’s good to know stuff, even if it doesn’t help one in his/her work directly. I probably owe it to Doppler Effect. Doppler Effect is this effect that we read in our high school physics (11th grade). It deals with the change in observed frequency of waves when the source moves w.r.t the observer or vice versa (both can move simultaneously too). I was amazed when I came to know that this very same effect was used to determine the evolution of the universe.yup. our entire universe.

Doppler Effect states that the observed frequency changes when there is motion btwn source n observer. It states tht the frequency increases when they are moving towards each other and decreases when they are moving away from each other. The observed frequency can be identified by the formula

f=((V+Vr)/(V+Vs))*f0






where

V is the velocity of waves in the medium

Vr is the velocity of the receiver relative to the medium; positive if the receiver is moving towards the source.

Vs is the velocity of the source relative to the medium; positive if the source is moving away from the receiver.

I still remember the way this effect was taught to me in high school. My teacher got the equation wrong and she tried to change the statement to fit the equation. It took a while for her to realize tht sth was wrong. She blamed the book, said it was incorrect n unclear. She gave us tips to remember the formula (“eppavume source keela varum observer mela varum. Enna maari thappa eluthatheenga ”) . She also said tht this was not tht important as there were more important questions in the same chapter. She asked us to remember the formula alone just in case they ask a problem for 2 marks. So I din really pay any attention to it either. I din read the uses section much. I knew it was used to measure the speed of a vehicle by traffic police. So when I came to know abt its other use I really was astounded.

We all know of Edward hubble and big bang theory. He said all galaxies are racing away from each other with a speed proportional to the distance between them. Hubble actually made use of Doppler effect to prove this. When he focussed the telescope on stars from other galaxies he observed a red shift in the spectrum, i.e. a decrease in frequency. He applied Doppler effect on light! Since light is a wave too.This means tht the source and observer are moving away from each other. He found tht all he could notice was red shift irrespective of the galaxy and the star he chose. This wld mean tht all galaxies are racing away from each other and if we look back in time they ll be racing towards each other and hence this shows that space is expanding.

Thus whenever I feel tht I m reading sth irrelevant (all subjects in the curriculum barring a very few), I automatically think of Doppler Effect. It made me believe that one can apply any theory onto anything as long as he/she finds the right analogy. Tht jack of all is actually better than king of one ..One good look at the applications of Doppler effect in wiki will give you an idea J.