vernier scale divisions will cover main scale divisions. ∴ VSD = MSD Or VSD = MSD Least count (LC) = MSD – VSD = × MSD= ′ = ′ OBSERVATION Table To find the angle of the prism (A) Image Vernier A (Degree) Vernier B (Degree) MSR VSC TR MSR VSC TR Reflected image from face Reflected image from face Difference 2A Mean 2A = Mean A = XII- - ) XII- - ) - - - - PRACTICAL Table To find the angle of minimum deviation (D) Image Vernier A (Degree) Vernier B (Degree) MSR VSC TR MSR VSC TR Refracted image Direct image Difference D Mean D = CALCULATION µ = sin sin D RESULT . Angle of the Prism (A) = ............ (degree) .
Angle of the minimum deviation of the prism (D) =............. (degree) . Refractive index of the material of the Prism (μ) =............. (No unit) 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