Question

In Newton’s rings experiment using light of two wavelengths , it is observed that 10 th order bright ring corresponding to wavelength 1 coincides with 15 th order dark ring corresponding to wavelength λ₂ when viewed by reflected light. Find the ratio of λ1 and λ₂

Answer 1

$r_1=\sqrt{\frac{m_1R\lambda_1}{n}},$

$r_2=\sqrt{\frac{m_2R\lambda_2}{2n}},$

$r_1=r_2,$

$\frac{\lambda_1}{\lambda_2}=\frac{m_2}{m_1}=1.5.$