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NEET-XII-Physics

20: dispersion and Spectra

with Solutions - page 4
Qstn# iv-8-a Prvs-QstnNext-Qstn
  • #8-a
    there is no net angular dispersion, and (b) there is no net deviation in the yellow ray.
    Figure (b) there is no net deviation in the yellow ray.
    Figure
    Ans : For zero angular dispersion, we have:
    δt - δt = 0 = 2(μvc -1)A - (μvf - 1)A'
    `` \Rightarrow \frac{A\text{'}}{A}=\frac{2({\mu }_{\,\mathrm{\,vf\,}}-1)}{({\mu }_{vc}-1)}``
    `` =\frac{2({\mu }_{r}-{\mu }_{r})}{({\mu }_{r}-\mu )}`` (b) For zero deviation in the yellow ray, δy = 0.
    ⇒ 2(μcy - 1)A = (μfy - 1)A
    `` \Rightarrow \frac{A\text{'}}{A}=\frac{2({\mu }_{\,\mathrm{\,cy\,}}-1)}{({\mu }_{\,\mathrm{\,fy\,}}-1)}``
    `` =\frac{2({\mu }_{y}-1)}{(\mu {\text{'}}_{y}-1)}``
    Page No 442:
    Page No 443: (b) For zero deviation in the yellow ray, δy = 0.
    ⇒ 2(μcy - 1)A = (μfy - 1)A
    `` \Rightarrow \frac{A\text{'}}{A}=\frac{2({\mu }_{\,\mathrm{\,cy\,}}-1)}{({\mu }_{\,\mathrm{\,fy\,}}-1)}``
    `` =\frac{2({\mu }_{y}-1)}{(\mu {\text{'}}_{y}-1)}``
    Page No 442:
    Page No 443:
  • #8-b
    there is no net deviation in the yellow ray.
    Figure
    Ans : For zero deviation in the yellow ray, δy = 0.
    ⇒ 2(μcy - 1)A = (μfy - 1)A
    `` \Rightarrow \frac{A\text{'}}{A}=\frac{2({\mu }_{\,\mathrm{\,cy\,}}-1)}{({\mu }_{\,\mathrm{\,fy\,}}-1)}``
    `` =\frac{2({\mu }_{y}-1)}{(\mu {\text{'}}_{y}-1)}``
    Page No 442:
    Page No 443: