AGreen, Blue, Orange, Golden
a
For normal incidence path difference between ray $1$ and ray $2$ is $2 \mu_{1}$ t
For minimum thickness increment $2 \mu_{1} \Delta \mathrm{t}=\frac{\lambda}{2}$
$\Rightarrow\left(t_{2}-t_{1}\right)=\frac{\lambda}{4 \mu_{1}}=\frac{9.6 \times 10^{-7}}{4 \times 1.2}=2 \times 10^{-7} \mathrm{\,m}$
$56 \mathrm{\,k} \Omega \pm 5 \%=56 \times 10^{3}\, \Omega \pm 5 \%$
Sequence : Green, Blue, Orange, Golden
