Find the ratio of de Broglie wavelength of a proton and an alpha-particle which have been accelerated through same potential difference.
22:1
3:2
32:1
2:1
de Broglie wavelength =λ=hmv=h2mqV
∴λpλα=mαqαVαmpqpVp Putting Vα=Vp,⇒λpλα=4×21×1=22