Question

The mass of electron is 9.1X10 -31 kg. If kinetic energy of the electron is 4.55X10 -25 .Calculate its wavelength.

Answer 1

kinetic energy=1/2mv^2
4.55 x 10^-25=1/2 x 9.1 x 10^-31 x v^2
v^2=(4.55/9.1) x 10^6 x 2
= 10^6
hence velocity of electron =10^3 m/sec
now use de-broglie concept
wavelength=h/mv
=6.626 x 10^-34/9.1 x 10^-31 x 10^3

=(6.626/9.1) x 10^-6 m

Answer 2

kinetic energy=1/2mv^2

4.55 x 10^-25=1/2 x 9.1 x 10^-31 x v^2

v^2=(4.55/9.1) x 10^6 x 2

= 10^6

hence velocity of electron =10^3 m/sec

now use de-broglie concept

wavelength=h/mv

=6.626 x 10^-34/9.1 x 10^-31 x 10^3

=(6.626/9.1) x 10^-6 m