The magnifying power of a telescope is high, if its objective and eyepiece have respectively

The ratio of speed of an electron in the ground state in the Bohr's first orbit of hydrogen atom to velocity of light $$(c)$$ is ( $$h=$$ Planck's constant, $$\varepsilon_0=$$ permittivity of free space, $$e=$$ charge on electron)

A charge $$q$$ moves with velocity $$v$$ through electric field $$\mathrm{E}$$ as well as magnetic field (B). Then, the force acting on it is

The force acting on the electrons in hydrogen atom (Bohr's theory) is related to the principle quantum number $$n$$ as