A Conducting Bar Moves as Shown near a Long Wire

Multiple Choice

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,V_a - V_b?

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