A particle of charge equal to that of an electron e , and mass 208 times the mass of electron (called $\;\mu-\;$ meson ) moves in a circular orbit around a nucleus of charge +3e . (Take the mass of nucleus to be infinite ) . Then radius of $n^{th}\;$ Bohr orbit is . Find wavelength of radiation emitted when $\;mu\;$- meson jumps from third orbit to first orbit

Question

$(a)\;0.692 A^{0}\qquad(b)\;0.548 A^{0}\qquad(c)\;0.312 A^{0}\qquad(d)\;0.212 A^{0}$