wave length of the prominent colours of the mercury light is determined using the given formula. XII- - ) XII- - ) - - - - PRACTICAL OBSERVATION To find the wave length of prominent colours of the mercury spectrum Colour of Light Diffracted Ray Reading (Degree) Difference θ (Degree) θ (Degree) Left Right Vernier A Vernier B Vernier A Vernier B MSR VSC TR MSR VSC TR MSR VSC TR MSR VSC TR VER A VER B Mean Blue Green Yellow Red CALCULATION (i) For blue, λ θ = sin nN , (ii) For green, λ θ = sin nN (iii) For yellow, λ θ = sin nN , (iv) For red, λ θ = sin nN RESULT . The wavelength of blue line = ----------------m . The wavelength of green line = ------------------m .
The wavelength of yellow line = ----------------m . The wavelength of red line = ----------------m Note: i) Once initial adjustments are done, spectrometer should not be disturbed. ii) Total reading TR = MSR + (VSC × LC) Where MSR → Main Scale Reading VSC → Vernier Scale Coincidence LC → Least count (= ′ ) XII- - ) XII- - ) - - - - PRACTICAL