Illustration of the scale/range  issue students faced in this class assigment. It is very easy and they can figure that out.  This one is in SI  but they can use (and did)  any other scale like nano etc.

c=3. 10^8

k=2 π/λ;λ=500. 10^(-9);ω=2 π ν;ν=c/λ;

λ

1/ν

Clear[t,x]

t=2. 10^-15

ϕ=0.

Plot[Sin[k x+ϕ]Cos[ω t],{x,0,60 10^-7},PlotRange->{-1,1},PlotLabel->"t  "   t]

Clear[t,x]

x=2. 10^-7

Plot[Sin[k x+ϕ]Cos[ω t],{t,0,20 10^-15},PlotRange->{-1,1},PlotLabel->"x  "   x]

Clear[x,t,ϕ]

Animate[Plot[{Sin[k x+ϕ]Cos[ω t],Sin[k x]Cos[ω t],5+Sin[k x+ϕ]Cos[ω t]+Sin[k x]Cos[ω t]},{x,0,60 10^-7},PlotRange->{{0,60 10^-7},{-2,7}},PlotLabel->"ϕ  "   ϕ],{t,0,20*10^-15},{ϕ,0,2π}, AnimationRunning->False]