Doubts

infinityzero
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Joined: Sun Jun 27, 2010 8:15 am

Doubts

Postby infinityzero » Mon Dec 06, 2010 3:22 pm

What could be the possible answer ?
Acco to me it should be option (B). But i am not sure about it.... :?:

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CarlBrannen
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Re: Doubts

Postby CarlBrannen » Mon Dec 06, 2010 7:30 pm

Here's another vote for (b).

If it were an infinite mass atom then it would be (a). With a finite mass, some of the energy of the photon will become kinetic energy of the energized atom. This means you need a little extra energy hence (b).

kroner
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Re: Doubts

Postby kroner » Wed Dec 08, 2010 10:30 am

To get the answer exactly, you can use the relation E^2 = (pc)^2 + (m_0c^2)^2, and the fact that the momentum of the atom after the collision is the same as the momentum of the photon, to get (Mc^2 + fh)^2 = (fh)^2 + ((M + \Delta)c^2)^2, and then solve for f.

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WhoaNonstop
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Re: Doubts

Postby WhoaNonstop » Wed Dec 08, 2010 1:14 pm

kroner wrote:To get the answer exactly, you can use the relation E^2 = (pc)^2 + (m_0c^2)^2, and the fact that the momentum of the atom after the collision is the same as the momentum of the photon, to get (Mc^2 + fh)^2 = (fh)^2 + ((M + \Delta)c^2)^2, and then solve for f.


Solving for f looks too haaaaaaaaard. :)

-Riley

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HappyQuark
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Re: Doubts

Postby HappyQuark » Wed Dec 08, 2010 1:32 pm

WhoaNonstop wrote:
kroner wrote:To get the answer exactly, you can use the relation E^2 = (pc)^2 + (m_0c^2)^2, and the fact that the momentum of the atom after the collision is the same as the momentum of the photon, to get (Mc^2 + fh)^2 = (fh)^2 + ((M + \Delta)c^2)^2, and then solve for f.


Solving for f looks too haaaaaaaaard. :)

-Riley


That's why Mathematica has the solve function. Just the other day I came across some really difficult algebra and had to have Mathematica break it down for me. How in the hell am I supposed to know how to solve x+2=4?

infinityzero
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Re: Doubts

Postby infinityzero » Fri Dec 10, 2010 5:04 pm

Thanks for the solution :D ..... please help me solve two more problems.........

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grae313
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Re: Doubts

Postby grae313 » Fri Dec 10, 2010 5:25 pm

Mind sharing where these problems are from?

infinityzero
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Joined: Sun Jun 27, 2010 8:15 am

Re: Doubts

Postby infinityzero » Fri Dec 10, 2010 5:40 pm

Well these problems are from last year's entrance exam for PhD(physics) program at TIFR,india... :D




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