A conducting rod with a mass of m lies in the middle of two frictionless conducting rods. The two rods have a separation of x. The uniform magnetic field (of magnitude B) in that region points downward. Should the current in the conducting rod flow in a direction from P to Q or from Q to P in order for the rod to roll to the left? 

• A. P to Q
• B. Q to P
• C. Magnetic force is not oriented left-right
• D. No magnetic force is experienced

Answer: (B)