A rigid wire carrying a steady current \(I\) lies in the plane of the page in a region containing a uniform magnetic field \(B\) directed perpendicularly into the page. The wire includes a semicircular arc of radius \(R\) with endpoints \(P\) and \(Q\) aligned horizontally, such that current flows through the arc from left to right (from \(P\) to \(Q\)). Which of the following expressions correctly gives the magnitude of the net magnetic force on the semicircular arc, and what is its direction?