A Conducting Bar Moves as Shown near a Long Wire

A conducting bar moves as shown near a long wire carrying a constant 80-A current.If a = 1.0 mm, b = 20 mm, and v = 5.0 m/s, what is the potential difference, Va-Vb?

A) (-0.24 mV)
B) +0.24 mV
C) (-0.19 mV)
D) +0.19 mV
E) (-0.76 mV)