help needed in phy p4...

[confused]

can sumone plz help me put wid these pastpaper questions?..:
may/june06 que 2bii
oct/nov03 que6cii..y is n reduced.? :?
and can sumone explain the principles of use ov magnetic resononace..?plzzzzz

 

[hussain_15_04]

for MRI:
human body made of hydrogen atoms
part that is to be examined is placed between huge magnet
atoms align themselves in the field of the magnet possessing a spinning motion known as precession
frequency of precession lamour frequency
radio frequency wave directed towards the part having lamour frequency
atoms resaonate absorbing energy
after a short while radio freqeuncy stops
atoms come to rest emmiting energy
transmitter now receiver receives energy
image is formed
i hope it helped

 

[confused]

thanks....

 

[Jazib]

oct nov 03.:
E=hc/lemda
Pt=hc/lemda
rearranging: lemda = hc/pt
now p,h,c is constant. also, 1/t = n
so it becomes lemda is directly proportional to n!
dats only what i cud come up with to xplain this, n may be wrong. if so, do correct me!
n dat may/june 06, i need xplaination too!
i knw it something related with P1V1=P2V2, but m not sure how does it ally here!