
#1
Oct2805, 09:20 AM

P: 741

for the following question:
a hydorgen atom is 5.3*10^(11) m in radius. use the uncertainty principle to estimate the minimum energy an electron acan have in this atom. my problem: to calculate the kinetic energy, do you use Ek=(p^2)/2m or Ek=pc???? 



#2
Oct2805, 09:32 AM

P: 1,017

The uncertainty principal is: /\x/\p = h/2*pi.
/\x is the radius you have stated. /\p is the uncertainty of momentum. p = mv, mass is known, so /\p = m/\v. So: /\v = h/(2 * pi * m * /\x) where m is the mass of the electron. Find /\v, then you can find the minimum energy: energy = 0.5 * m * /\v^2. 



#3
Oct2905, 05:04 AM

P: 741

is that the same as just calculating the kinetic energy=p^2/2m?




#4
Oct2905, 06:03 AM

P: 1,017

de broglie waves
Yep, that's another way.




#5
Oct3105, 08:00 AM

P: 741

ok~ that's cool!



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