The diffraction pattern of a light of wavelength \(400 \mathrm{~nm}\) diffracting from a slit of width \(0.2 \mathrm{~mm…

The diffraction pattern of a light of wavelength \(400 \mathrm{~nm}\) diffracting from a slit of width \(0.2 \mathrm{~mm}\) is focused on the focal plane of a convex lens of focal length \(100 \mathrm{~cm}\). The width of the \(1^{\text {st }}\) secondary maxima will be :