The trace identity associated with the scale transformation e?‘￥e??? a?’ e?‘￥a€2e??? = e?‘’-?? e?‘￥e??? on the Lagrangian density for the noninteracting electromagnetic field in the covariant gauge is shown to be violated on a single plate on which the Dirichlet boundary condition e??′e???(e?‘?; e?‘￥1, e?‘￥2, e?‘￥3 = -e?‘?) = 0 is imposed. It is however respected in free space, i.e. in the absence of the plate. These results reinforce our assertions in an earlier paper where the same exercise was carried out using the Lagrangian density for the free, massive, real scalar field in 2 + 1 dimensions.
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