White light is passed through a double slit and interference is observed on a screen \( 1.5 \, \text{m} \) away. The separation between the slits is \( 0.3 \, \text{mm} \). The first violet and red fringes are formed \( 2.0 \, \text{mm} \) and \( 3.5 \, \text{mm} \) away from the central white fringes. The difference in wavelengths of red and violet light is ______ \( \text{nm} \).
