If the monochromatic source in Young's double slit experiment is replaced by white light, then:

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1. **Central Maximum:** At the central point on the screen, the path difference between the light waves arriving from the two slits is zero ($\Delta x = 0$). The condition for constructive interference ($\Delta x = n\lambda$) is satisfied for all wavelengths (colors) when $n=0$. Therefore, all wavelengths overlap constructively at the center, resulting in a **central white fringe**.
2. **Coloured Fringes:** For positions away from the center, the path difference is non-zero. The position of the $n$-th bright fringe is given by $y_n = \frac{n \lambda D}{d}$. Since the wavelength $\lambda$ varies for different colors ($\lambda_{red} > \lambda_{violet}$), the maxima for different colors occur at different positions. The violet fringe (shortest $\lambda$) forms closest to the central maximum, followed by other colors, with red appearing furthest. This results in a few coloured fringes surrounding the central white fringe.
3. **Fringe Width:** The fringe width is $\beta = \frac{\lambda D}{d}$. Since $\lambda$ is different for each color, the fringe widths are not equal.

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