What does it mean if the $\alpha -$ particle passes through the foil of gold ?
When the accelerating voltage applied on the electrons increased beyond a critical value
Why atoms are electrical neutral ?
An electron makes a transition from orbit $n = 4$ to the orbit $n = 2$ of tha hydrogen atom. The wave number of the emitted radiations ($R =$ Rydberg's constant) will be
The radius of the smallest electron orbit in hydrogen-like ion is $(0.51/4 \times 10^{-10})$ metre; then it is
When an $\alpha -$particle of mass $m$ moving with velocity $v$ bombards on a heavy nucleus of charge $Z_e$ , its distance of closest approach from the nucleus depends on $m$ as