A very small charged block with a mass of 2.35 g is placed on an insulated, frictionless plane inclined at an angle of $17.0^{\circ}$ with respect to the horizontal. The block does not slide down the
plane because of a $465-\mathrm{N} / \mathrm{C}$ uniform electric field that points parallel to the surface downward along the plane. What is the sign and magnitude of the charge on the block?