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
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.