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stunner5000pt
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A lithium atom (mass doesn't matter) is being pushed from rest by a laser beam whose power is 1mW. Find the velocity of this lithium atom as a function of time
So here goes what i have done
[tex] v(t) = \frac{1}{2} at^2 [/tex]
now [tex] F = ma = \frac{\Delta p}{\Delta t} [/tex]
so then [tex] a = \frac{\Delta p}{\Delta t m} [/tex]
and then subbing into the first equation
[tex] v(t) = \frac{1}{2} \frac{\Delta p}{m \Delta t} t^2 [/tex]
[tex] v(t) = \frac{\Delta p t}{2m} [/tex]
The radiation pressure becasue of the lithium absorbing (right?) is given by
[tex] \Delta p = \frac{\Delta U}{c} [/tex]
so then [tex] v(t) = \frac{\Delta U}{c} \frac{t}{2m} [/tex]
and [tex] \Delta U = P t = 0.001t [/tex] P = 1mW
[tex] v(t) = \frac{0.001t^2}{2mc} [/tex]
am i right in assuming that the lithium atom will absorb jump to higher level and then go back down? Because i do know that the lifetime of the lithium atom in the ecited state is 27ns
If this is not clear to you you might want to have a look at the b part of the question posted in thsi thread
https://www.physicsforums.com/showthread.php?t=64390
thanks in advance for your help!
So here goes what i have done
[tex] v(t) = \frac{1}{2} at^2 [/tex]
now [tex] F = ma = \frac{\Delta p}{\Delta t} [/tex]
so then [tex] a = \frac{\Delta p}{\Delta t m} [/tex]
and then subbing into the first equation
[tex] v(t) = \frac{1}{2} \frac{\Delta p}{m \Delta t} t^2 [/tex]
[tex] v(t) = \frac{\Delta p t}{2m} [/tex]
The radiation pressure becasue of the lithium absorbing (right?) is given by
[tex] \Delta p = \frac{\Delta U}{c} [/tex]
so then [tex] v(t) = \frac{\Delta U}{c} \frac{t}{2m} [/tex]
and [tex] \Delta U = P t = 0.001t [/tex] P = 1mW
[tex] v(t) = \frac{0.001t^2}{2mc} [/tex]
am i right in assuming that the lithium atom will absorb jump to higher level and then go back down? Because i do know that the lifetime of the lithium atom in the ecited state is 27ns
If this is not clear to you you might want to have a look at the b part of the question posted in thsi thread
https://www.physicsforums.com/showthread.php?t=64390
thanks in advance for your help!
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