Give a powerful way to determine an upper limit to the size of the electron.
The wavelength of ${K_\alpha }$ line for an element of atomic number $29$ is $\lambda $ . Then the wavelength of ${K_\alpha }$ line for an element of atomic no $15$ is (Take mosley‘s constant $b = 1$ for both elements)
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
Which scientist gave plum pudding model of the atom ?
In an atom, two electrons move around the nucleus in circular orbits of radii $R$ and $4R.$ The ratio of the time taken by them to complete one revolution is : (neglect electric interaction)
What does it mean if the $\alpha -$ particle passes through the foil of gold ?