Wavelength= 12.27/ under root V
= 12.27/ 120 root
= 12.27/ 11
= 1.115 Angastron
= 112 pickometer

Calculating the de Broglie Wavelength of an Electron
To calculate the de Broglie wavelength of an electron with kinetic energy of 120eV, we can use the formula:
λ = h / p
where
λ is the de Broglie wavelength,
h is the Planck constant (6.626 x 10^-34 m^2 kg / s), and
p is the momentum of the electron.

Calculating Momentum
The momentum (p) of an electron can be calculated using the formula:
p = √(2mE)
where
m is the mass of the electron (9.11 x 10^-31 kg), and
E is the kinetic energy of the electron (120eV).
Substitute the values of m and E into the formula to find the momentum of the electron.

Calculating the de Broglie Wavelength
Once you have calculated the momentum of the electron, you can then use it in the de Broglie wavelength formula to find the wavelength of the electron.
Substitute the calculated momentum value into the de Broglie wavelength formula along with the Planck constant to find the de Broglie wavelength of the electron.

Conclusion
By following these steps and using the appropriate formulas, you can calculate the de Broglie wavelength of an electron with a kinetic energy of 120eV. This wavelength will give you insight into the wave-like behavior of the electron at this energy level.