Question

An electron has de Broglie wavelength 2.81×10−10 m Determine the kinetic energy Ke of the electron. Express your answer in joules to three significant figures. THE ANSWER IS NOT 1.29*10^4

Answer 1

Kinetic energy = p^2 / 2m

p is momentum and equal to h/

h is plank's constant , 6.62×10^-34 kg m^2/s

is de Broglie wavelength of electron

m is mass of electron , 9.1×10^-31 kg

Kinetic energy = h^2 / ^2 2 m

= 6.62^2×10^-68 / 2.81^2×10-20 * 2*9.1×10-31

= 3.05×10^-18 J