How is this an improvement on the traditional, paper coffee filters? a: they are less wasteful and more cost effective because they last longer b: a permanent filter is more expensive than a traditional filter c: they contain plastic which does not break down as easily as paper d: the coffee brewed using permanent filters does not taste as good?
the answer to your question would be a. angle at which the ray strikes the medium
so this website should . i kinda don't know myself and don't want you to get this answer wrong: )
i believe it is d: horizontally!