The electromagnetic tensor is the combination of the electric and magnetic fields into a covariant antisymmetric tensor whose entries are B -field quantities. F α α β β = ( 0 E x / c E y / c E z / c − − E x / c 0 − − B z B y − − E y / c B z 0 − − B x − − E z / c − − B y B x 0 ) and the result of raising its indices is F μ μ ν ν = d e f η η μ μ α α F α α β β η η β β ν ν = ( 0 − − E x / c − − E y / c − − E z / c E x / c 0 − − B z B y E y / c B z 0 − − B x E z / c − − B y B x 0 ) , where E is the electric field, B the magnetic field, and c the speed of light.