Answer: 50.2 nm
Explanation:
The relation between energy and wavelength of light is given by Planck's equation, which is:
[tex]E=\frac{hc}{\lambda}[/tex]
where,
E = energy of the light = 3.94aJ= [tex]3.94\times 10^{-18}J[/tex] [tex]1aJ=10^{-18}J[/tex]
h = Planck's constant =[tex]6.6\times 10^{-34}Js[/tex]
c = speed of light =[tex]3.0\times 10^8ms^{-1}[/tex]
[tex]\lambda[/tex] = wavelength of light = ?
Putting all the values we get:
[tex]3.94\times 10^{-18}=\frac{6.6\times 10^{-34}\times 3.0\times 10^8}{\lambda}[/tex]
[tex]\lambda=5.02\times 10^{-8}m=50.2nm[/tex] [tex]1nm=10^{-9}m[/tex]
Thus the wavelength of light, in nanometers that is just sufficient to ionize a helium atom is 50.2 nm
