For maximum transmission (minimum reflection), destructive interference of reflected waves is needed. Since light goes from lower \(n\) (air) to higher \(n\) (film), and film \(n >\) glass \(n\), only one phase reversal occurs. Condition: \(2\mu t = \lambda \Rightarrow t = \frac{\lambda}{2\mu} = \frac{550}{2\times2} = 137.5\) nm.