Remember the formula:
n = sin i / sin r = v1 / v2 = λ1 / λ2 = n2 / n1
n = Refractive index
i = angle of incidence
r = angle of refraction
λ = wavelength
v = velocity
Here are some worksheets for last minute revision.
http://img149.imageshack.us/img149/583/scan0002xc7.jpg...
Re: How long are your periods??
Yup, I agree with Kirsty Xx. If you can't handle it. You fail Aplus. You're Weak (Y)
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