Plot[Sin[x],{x,0,2Pi}]

Plot[Sin[x],{x,0,2Pi},AspectRatio->Automatic]

Plot[Sin[x],{x,0,2Pi},PlotPoints->10]

Plot[Sin[x],{x,0,2Pi},PlotPoints->10,MaxRecursion->0]

Plot3D[Sin[Pi x]Sin[Pi y/2],{x,0,1},{y,0,2}]

Plot3D[Sin[Pi x]Sin[Pi y/2],{x,0,1},{y,0,2},BoxRatios->Automatic]

Plot3D[Sin[Pi x]Sin[Pi y/2],{x,0,1},{y,0,2},BoxRatios->{1,2,1/2},PlotRange->{-1,1}]

Table[
Plot3D[Sin[m Pi x]Sin[n Pi y/2],{x,0,1},{y,0,2},BoxRatios->Automatic],{m,1,2},{n,1,2}]

Table[Plot3D[Sin[m Pi x]Sin[n Pi y/2],{x,0,1},{y,0,2}],{m,1,1},{n,1,20}]

Plot3D[Sin[ Pi x]Sin[14 Pi y/2],{x,0,1},{y,0,2},PlotRange->All]

Plot3D[Sin[ Pi x]Sin[14 Pi y/2],{x,0,1},{y,0,2},PlotPoints->15]

Plot3D[Sin[ Pi x]Sin[100 Pi y/2],{x,0,1},{y,0,2},PlotPoints->{20,101}]

c=1;
l=1;
w=2;
m=2;
n=2;
μ=m Pi/l;
ν=n Pi/w;
ω=c Sqrt[(m/l)^2+(n/w)^2]Pi;
Animate[
Plot3D[Cos[ω t]Sin[μ x]Sin[ν y],{x,0,l},{y,0,w},
PlotRange->{-2,2},Mesh->True,PlotPoints->20,BoxRatios->{1,2,1}],
{t,0,2Pi/ω}]

Table[4m^2+n^2,{m,1,4},{n,1,4}]

c=1;
l=1;
w=2;
m=2;
n=2;
μ=m Pi/l;
ν=n Pi/w;
ω=c Sqrt[(m/l)^2+(n/w)^2]Pi;
Animate[
Plot3D[Cos[ω t]Sin[μ x]Sin[ν y]+Cos[ω t]Sin[Pi x]Sin[4Pi y/2],{x,0,l},{y,0,w},
PlotRange->{-2,2},Mesh->True,PlotPoints->20,BoxRatios->{1,2,1}],
{t,0,2Pi/ω}]