A transparent semicylinder has refractive index `mu = sqrt(2)` . A parallel beam of light is incident on its plane surface making an angle of `45°` with the surface. The incident beam extends from O to A on the plane surface. Find the maximum width OA (in terms of radius R of the cylinder) so that no ray suffers total internal reflection at the curved surface. [O is the centre of the circular cross section of the cylinder]
