Question

Calculate wavelength of light using biprism

Answer 1

Measurement of d Without changing the position of the slit, biprism and the eye-piece; a convex lens is mounted on the optical bench between the latter two. The distances d1 and d2 between the well-defined images of the two virtual slits S1 and S2 are measured with the micrometer screw for the two positions of the lens as shown in (Figure 4). Then the distance between S1 and S2 is given by d = √(d1d2) If the convex lens is not well chosen, the distance d2 between the images of the slit in the second case (giving diminished images) becomes very small and the measurement become too erratic.