Optical properties of a braneworld black hole: Gravitational lensing and retrolensing

In this paper, we study optical properties in terms of weak and strong (retrolensing) gravitational lensing around a black hole on the brane. The black hole is described by the Reissener-Nordstr\"om metric, where the electric charge is replaced by the Weyl tidal charge which acts in consonance with mass. It is, therefore, expected that gravitational lensing effects would be enhanced by the tidal charge, and that is what we verify. We also study the shadow of a braneworld black hole in plasma and show that the tidal charge increases the size of the black hole shadow. We finally consider energy emission from the hole by thermal radiation which is also increased due to tidal charge.