Answer
The P point in the two-slit interference pattern is between the sixth minima $(m=6.5)$ and the seventh maximum $(m=7)$.
Work Step by Step
The angular locations of the bright fringes of the double-slit interference pattern are
given by
$d\sin\theta=m\lambda$
or, $m=\frac{d\sin\theta}{\lambda}\;.........(1)$
In the part (a) of this question, we have calculated $\theta=0.173\;rad$
Substituting the known values in eq. 1, we obtain
$m=\frac{24\times10^{-6}\sin0.173}{600\times10^{-9}}$
or, $m=6.89$
The value of $m$ suggests that the angle corresponds to a point which is between the sixth $(m=6)$ and the seventh maximum $(m=7)$. Between the sixth $(m=6)$ and the seventh maximum $(m=7)$, there is sixth minima at $m=6.5$.
Therefore, the P point in the two-slit interference pattern is between the sixth minima $(m=6.5)$ and the seventh maximum $(m=7)$.
