Question

calculate the wave length of alpha particle accelerated by 20 volts ?

Answer 1

Question 33177

When alpha-particle is accelerated by potential $U = 20V$ , it has energy $E = qU = 2eU$ (the charge of alpha-particle is $q = 2e$ ).

Since the energy of the alpha-particle is $E = h\nu = \frac{hc}{\lambda}$ , obtain

$$2 e U = \frac {h c}{\lambda} \Rightarrow \lambda = \frac {h c}{2 e U} = 3. 1 \cdot 1 0 ^ {- 6} m = 3 1 n m.$$