In a double slit experiment using light from a helium-neon laser, a student obtained the following results:
width of 10 fringes = 1.5 cm
separation of slits a = 1.0 mm
slit-to-screen distance D = 2.40 m
Determine the wavelength of light.
To solve the problem, I have to find the fringe separation. If I divide $1.5$ by $10$, I would get the width of $1$ fringe. Is that the same thing as the fringe separation?
A diagram showing what the fringe separation is would be really helpful. The textbook that I'm currently reading defines the fringe separation as the distance between the centres of adjacent bright fringes. What does that mean?