A Conducting Rod Whose Length Is $\ell = 27.0 \mathrm {~cm}$

Multiple Choice

A conducting rod whose length is $\ell = 27.0 \mathrm {~cm}$ is placed on frictionless $U$ -shaped metal rails that is connected to a lightbulb having a resistance of $5.00 \Omega$ as shown in the figure. The rails and the rod are in the plane of the page. A constant uniform magnetic field of strength $1.20 \mathrm {~T}$ is applied perpendicular to and out of the paper. An external applied force moves the rod to the right with a constant speed. At what speed should the rod be pulled so that the lightbulb will consume energy at a rate of $1.10 \mathrm {~W}$ ?

A) $4.26 \mathrm {~m} / \mathrm { s }$
B) $3.50 \mathrm {~m} / \mathrm { s }$
C) $7.24 \mathrm {~m} / \mathrm { s }$
D) $6.00 \mathrm {~m} / \mathrm { s }$
E) $2.00 \mathrm {~m} / \mathrm { s }$