What precaution must be taken?
optical laser with output of 1mW or less
ensure it is not pointed directly into anyones eyes
use matt paper
What should the conditions be in the lab?
How is fringe seperation measured?
mark the visible fringes
count the fringes
central fringe is not included
use reuler to measure D
how is slit separation measured?
with Vernier calipers
What would the graph show?
w against D
should be a straight line through the origin
what does the gradient of the graph show?
λ / s