1.1 Prims. The deviation suffered by a ray on traversing a prism with apex angle a is given by 9 = a(n 1). The derivative of 8 with respect to n is 80 = aSn, and substitution of a from the first equation gives 89=9 --. (2) n 1 Hence the dispersive power, from Eq. (1), is simply Yp =. Usmg the spectral lines J c and d, we can n i write the Resolving power Spectral lines Aim of the experiment To determine the wavelengths of the prominent lines of mercury by a plane transmission diffraction grating, hence to find (a) the chromatic resolving power of the plane transmission diffraction grating and (b) the Turn the prism table from this position through 450 or 1350, so that Website for virtual Laboratory: vlab.amrita.edu/index.phpDo check the video tutorial on virtual lab experiment:youtube.com/watch?v=Nz1ybT Resolving power is directly proportional to diameter of objective lens and inversely proportional to . i.e., a telescope with large diameter of objective lens has higher resolving power. (here D distance between objective and source, d: separation between slits) Q. 5. For which colour of light, the resolving power of telescope will be large? • Measuring the Angle of PrismA: Place the prism on the Prism Table and lock the prism table in the position so the the incident beam falls on one of the edges of the prism. Now, move the telescope and locate the images of the slit and note down the Angles. The difference beteen both the angles is 2A. Hence, half of the diffece will give us A. lines for measurements on a dispersing prism in section d. Check your results for λ against those in the wavelength tables in the laboratory, or in Table 3.3 in Hecht (p. 70). c. Chromatic Resolving Power of a Diffraction Grating Diffraction of light that passes an aperture may limit the resolution of an instrument. However, At this stage the two sources are just resolved and the angle subtended by the sources is the minimum angle of resolution. Take a measurement of the width of the rectangular slit. - Now reduce the width of the rectangular slit till the two sources are completely unre- solved. The corresponding resolving power R 1 deduced on the basis of Rayleigh's criterion is: R = l/Dl = bdn/l where n is the refractive index of the prism for the wavelength l and b is the maximum thickness of the prism traversed by light rays. The quantities dn/dl and b often are called the dispersion and baselength of the prism, respectively. Dispersion and resolving power of the prism and grating spectroscope 2.1.03-00 Geometrical Optics Optics Principle: The refractive indices of liquids, crown glass and flint glass are deter-mined as a function of the wave-length by refraction of light through the prism at minimum deviation. The resolving power of the glass prisms is d = λ/ (2n sin θ) Thus, the resolving power of microscope is (R.P)m = (2n sin θ)/λ The expression (2n sin θ) is called numerical aperture (N.A). The highest value of N.A of the objective obtainable in practice is 1.6, and for the eye, N.A is 0.004. 12.2.b SPECTRAL RESOLVING POWER. The spectral resolving power R, a dimensionless measure of the limit of resolution, is defined as R = λ / δ λ, hence. (12.2.3) R = λ δ λ = λ A r ϕ d 1 D ⋅. It is clear from Eq. (12.2.3) that a larger telescope requires a larger beam diameter for a given type of disperser, if the resolving power is to The term resolving power is applied to spectrographic devices using a prism or a grating. Resolving