Describe Geiger-Marsden scattering experiment.
As shown in above figure, they directed a beam of $5.5 \mathrm{MeV} \alpha$-particle emitted from a ${ }_{83}^{214} \mathrm{Bi}$ radioactive source at a thin metal foil made of gold. $\alpha$-particles emitted by a ${ }_{83}^{214} \mathrm{Bi}$ radioactive source were collimated into a narrow beam by their passage through lead bricks. As shown in the figure below, the beam was allowed to fall on a thin foil of gold of thickness $2.1 \times 10^{-7} \mathrm{~m}$.
The scattered $\alpha$-particles on striking the screen produced brief light flashes (scintillations).
These flashes may be viewed through a microscope and the distribution of the number of scattered particles may be studied as a function of angle of scattering.
In the Rutherford's nuclear model of the atom, the nucleus (radius about $10^{-15} \;m$ ) is analogous to the sun about which the electron move in orbit (radius $\approx 10^{-10} \;m$ ) like the earth orbits around the sun. If the dimensions of the solar system had the same proportions as those of the atom, would the earth be closer to or farther away from the sun than actually it is? The radius of earth's orbit is about $1.5 \times 10^{11} \;m.$ The radius of sun is taken as $7 \times 10^{8}\;m$
The diagram below shows the lowest four energy levels for an electron in a hypothetical atom.The electron is excited to the $-1\,eV$ level of the atom and transitions to the lowest energy state by emitting only two photons. Which of the following energies could not belong to either of the photons ? .....$eV$
In gold foil experiment number of deflected $\alpha -$ particles at angle $90^o$ is $63$ than number of $\alpha -$ particle deflected at $120^o$ is
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)