A single current-carrying circular loop of radius R is placed next to a long,straight wire,as shown in the figure.The current I in the wire flows to the right.In which direction must current flow in the loop to produce a net magnetic field of zero at its center?
A)counterclockwise
B)clockwise
C)It could be either clockwise or counterclockwise.
D)The current in the loop should be zero.

Question

A single current-carrying circular loop of radius R is placed next to a long,straight wire,as shown in the figure.The current I in the wire flows to the right.In which direction must current flow in the loop to produce a net magnetic field of zero at its center? 
A)counterclockwise 
B)clockwise 
C)It could be either clockwise or counterclockwise. 
D)The current in the loop should be zero.

Quizplus · Accepted Answer

According to the right-hand rule, when the current flows in the long straight wire to the right, the magnetic field around the wire is directed counterclockwise. To cancel out this magnetic field, the magnetic field produced by the current in the circular loop must be directed clockwise. Therefore, the current in the loop must also flow clockwise.

A Single Current-Carrying Circular Loop of Radius R Is Placed