Velocity of Electron ionized from Hydrogen

[DRC12]

Homework Statement

Ultraviolet light with a wavelength of 45.0nm shines on a gas of hydrogen atoms in their ground states. Some of the atoms are ionized by the light. What is the kinetic energy of the electrons that are freed in this process?
I found the kinetic energy right but for some reason I thought I was looking velocity and when I solve for velocity I get a number much larger then the speed of light

Homework Equations

k=.5mv²
k=14eV
m=9.11*10^-31kg

The Attempt at a Solution

k=.5mv²
v²=2k/m
v=√(2*14/9.11*10^-31)=5.54*10¹⁵m/s
am I doing something wrong or is there some quantum equation needed

 

[ehild]

Homework Statement

Ultraviolet light with a wavelength of 45.0nm shines on a gas of hydrogen atoms in their ground states. Some of the atoms are ionized by the light. What is the kinetic energy of the electrons that are freed in this process?
I found the kinetic energy right but for some reason I thought I was looking velocity and when I solve for velocity I get a number much larger then the speed of light

Homework Equations

k=.5mv²
k=14eV
m=9.11*10^-31kg

The Attempt at a Solution

k=.5mv²
v²=2k/m
v=√(2*14/9.11*10^-31)=5.54*10¹⁵m/s
am I doing something wrong or is there some quantum equation needed

Find the kinetic energy in joules, and calculate the speed with that value. Now you have the speed in units of eV^0.5kg^-0.5 instead of m/s.

ehild

 

[DRC12]

Oh, thanks, I keep forgetting about that. I really need to start writing down the units

 

[ehild]

Oh, thanks, I keep forgetting about that. I really need to start writing down the units

It is a good idea !

ehild