Wave function of the radion in a brane world

We calculate the linearized metric perturbation corresponding to a massless four-dimensional scalar field, the radion, in a five-dimensional two-brane model of Randall and Sundrum. In this way we obtain the relative strengths of the radion couplings to matter residing on each of the branes. The results are in agreement with the analysis of Garriga and Tanaka of gravitational and Brans-Dicke forces between matter on the branes. We also introduce a model with an infinite fifth dimension and ``almost'' confined graviton, and calculate the radion properties in that model.