Letm1,m2be the masses andv1,v2be the velocities for electron and proton respectively .As the two particles have same kinetic energy , therefore1/2m1v21=1/2m2v22=Eorm1v1=√2m1Eandm2v2=√2m2Esincem1<m2orm1v1<m2v2.As de-Broglie wavelength ,λ=h/mv, it means that de-Broglie wavelength for electron is greater .