The mass of an electron is 9.1 × 10⁻³¹ kg. If its K.E. is 3.0 × 10⁻²⁵ J. Calculate its wavelength.

Given that,
The mass of an electron=m=9.1 × 10⁻³¹ kg.
K.E.=3.0 × 10⁻²⁵ J
The velocity of the electron is obtained from its kinetic energy.
v=√(2KE/m) = √(2 × 3.0 × 10⁻²⁵ / 9.1 × 10⁻³¹ ) = 812 m/s
The wavelength of electron is,
λ = h/mv
h=Plank's constant=6.626 × 10⁻³⁴ Js
λ = (6.626 × 10⁻³⁴) / (9.1 × 10⁻³¹ × 812) = 8953 × 10⁻¹² m = 8953 Å