Question

(a) An electron has kinetic energy 6.00 eV. Find its wavelength. m (

b) A photon has energy 6.00 eV. Find its wavelength. m

Answer 1

Planck's constant = h = 6.626 x 10^-34 m²kg/s

Part A :

Kinetic energy of electron = E = 6 eV = 9.6 x 10^-19 J

Mass of electron = m = 9.1 x 10^-31 kg

Momentum of the electron = P = mv

E = mv²/2

E = P²/2m

P = 1.322 x 10^-24 kg.m/s

Wavelength of the electron =

= 5.012 x 10^-10 m

Wavelength of electron with kinetic energy of 6 eV = 5.012 x 10^-10 m

Part B :

Energy of photon = E = 6 eV = 9.6 x 10^-19 J

Speed of light = c = 3 x 10⁸ m/s

Wavelength of photon =

= 2.07 x 10^-7 m

Wavelength of photon with 6 eV energy = 2.07 x 10^-7 m