Question

The mass of an electron is 9.1 x 10 -31 kg. If its kinetic energy is 3.0 x 10 -25 J, calculate its wavelength.

Answer 1

we know

wavelength=h/mv. (h is constant=6.626×10^-36)

wavelength=h/mv=h/p

also we know

p=(2m×E)^1/2

put this value of P in debrogile,'s eqaution

so

wavelength=h/(2m×E)^1/2

we know

m=9×10^-31. (approx)

E=3×10^-25

then

wavelength=(6.626×10^-34)/(9×10^-31×2×3×10^-25)^1/2

wavelength=6.626×10^-34/(54×10^-56)^1/2

wavelength=(6.626×10^-34)/7.3×10^-28

=.9×10^-6

=9×10^-7(approx value)

hope it helps