A conducting bar of mass \(m\) and length \(\ell\) slides down two frictionless parallel conducting rails inclined at an angle \(\theta\) above the horizontal. The rails are separated by a distance \(\ell\) and are connected at the top by a resistor of resistance \(R\), forming a closed circuit. A uniform magnetic field of magnitude \(B\) is directed perpendicular to the plane of the rails. If the electrical resistance of the bar and rails is negligible, which of the following expressions represents the terminal speed \(v_{\text{term}}\) of the bar?