Question

Light from a source of wavelength 475 nm passes through a single slit and falls on a screen 2.5 m away. If the slit width is 2.00 μm, how many maxima occur, including the central maximum?

Answer 1

$$d \sin \theta = n\lambda$$

$$n_{max}=\frac{d}{\lambda}=\frac{2}{0.475}=4$$

Thus, there are 4 minima from each side of  the central maximum. So, there are

$$2(4-1)+1=7$$

maxima including the central maximum.