Question

How does the de Broglie wavelength of an electron change if its momentum increases?

How does the de Broglie wavelength of an electron change if its kinetic energy decreases?

Answer 1

debroglie wavelength of a mass m, velocity v is given by
lambda = h/mv

a. so when momentum mv increases, lambda (debroiglie wavelength) decreases
-> Option 2
b. KE = 0.5mv^2
   v = sqroot(2KE/m)
   so, lambda = h/m*sqroot(2KE/m) = h/sqroot(2KE*m)

   so when KE decreases, lambda ijncreases
   hence option -> 1