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.An external applied force moves the rod to the right with a constant speed of 6.00 m/s.At what rate is energy dissipated in the lightbulb?

A) 60.0 W
B) 121 W
C) 21.2 W
D) 112 W
E) 11.5 W