b
\(\frac{{d\lambda }}{\lambda }\,\, \times \,\,100\,\, = \,\,0.5\)  \( \Rightarrow \,\,\frac{{d\lambda }}{\lambda }\, = \,\,\frac{{0.5}}{{100}}\,\, = \,\,\frac{1}{{200}}\,\) અને 

\(\Delta \,P\,\, = \,\,{P_m}\)

\(\,\,p\,\, = \,\,\frac{h}{\lambda }\) વિકલન કરતાં \(\,\frac{{dp}}{{d\lambda }}\,\, = \,\, - \,\frac{h}{{{\lambda ^2}}}\,\, = \,\, - \,\frac{h}{\lambda }\,\, \times \,\,\frac{1}{\lambda }\,\, = \,\, - \frac{p}{\lambda }\)

\( \Rightarrow \,\,\frac{{|dp|}}{p}\,\, = \,\,\frac{{d\lambda }}{\lambda }\)

\(\therefore \,\,\frac{{{P_m}}}{p}\,\, = \,\,\frac{1}{{200}}\,\,\, \Rightarrow \,\,p\,\, = \,\,200\,\,{P_m}\)