f[k_,b_,x_,y_]:=((Sin[k x+b])^2)

g2[k_,b_]:=DensityPlot[f[k ,b,x,y],{x,-π,π},{y,-.75,.75},ColorFunction->{Blend[{White,Green,White},#]&},Frame->False,AspectRatio->.8,Epilog->{White,Polygon[{{-π,1},{π,.75},{π,0},{-π,.75}}],Polygon[{{π,-.75},{-π,-1},{-π,0},{π,-.75}}],Thick,Black,Line[{{-π,.75},{π,0},{π,-.75},{-π,0},{-π,.75}}]},ImageSize->{275,350}]

g1[b_]:=Graphics[{RGBColor[.25,.43,.82],Thickness[.1],Line[{{1,-1},{1,-5}}],PointSize[.1],Point[{1,-5.4}],LightBlue,PointSize[.1],
Point[{1,-0.455}],
Opacity[Boole[b>0]],RGBColor[.25,.43,.82],Arrowheads[.08],Thickness[.02],Arrow[{{1,-0.5},{1,1+.2b}}],Text[Style["B",24,Bold,RGBColor[.25,.43,.82]],{0,0.5+.2b}],
Opacity[1],LightGray,EdgeForm[{Thick,Black}],Polygon[{{-3,0},{3,-3},{3,-5.75},{-3,-2.75},{-3,0}}],Thickness[.02],Black,Line[{{-1,-3.4},{-1,-1.4}}],Line[{{1,-4.4},{1,-2.4}}],Thickness[.01],White,Line[{{-1,-3.4},{-1,-1.4}}],Line[{{1,-4.4},{1,-2.4}}],
Rotate[{Black,Thickness[.005],Arrowheads[.05],Table[Arrow[{{-6,-5},{-3-.4z,.6z}}],{z,-12,-5,1}],

Thickness[.1],Gray,Line[{{-9,-5},{-6.5,-5}}],PointSize[.1],Point[{-5.5,-5}],Black,Point[{-9.5,-5}]},20°,{-5.5,-5}]
},
PlotRange->{{-11,6},{-9,8}},ImageSize->{275,350}]

Manipulate[
GraphicsRow[{g1[b],g2[k,b]},Spacings->0],
{{k,1,"Momento do Electrão"},1,3},
{{b,0,"Campo Magnético"},0,10},ControlPlacement->Top,
TrackedSymbols->True,SaveDefinitions->True]