First you find the Momentum (P) from the de Broglie eqn: P = h/lambda, where h is the Plancks constant. Then you find the velocity (v) from the eqn: P = m*v, where m is the Electron Mass. Then substitute v in the KE eqn: KE = 0.5*m*v^2. Add this KE to the Ionization Energy of ...
For Further Reading