A Conducting Rod Whose Length Is ℓ = 1

Multiple Choice

A conducting rod whose length is ℓ = 1.60 m is placed on frictionless U-shaped metal rails that is connected to a lightbulb having a resistance of 4.00 Ω as shown in the figure.The rails and the rod are in the plane of the page.A constant uniform magnetic field of strength 2.20 T is applied perpendicular to and out of the paper.What is the magnitude of the external applied force needed to move the rod to the right with a constant speed of 6.00 m/s?

A) 8.60 N
B) 9.30 N
C) 10.6 N
D) 12.6 N
E) 18.6 N