A conducting loop is being withdrawn from a magnetic field at a speed v , as depicted in the figure. Which of the four plots shown in the figure could represent the power delivered by the pulling agent as a function of the speed v ?

Step-by-step solution

The motional emf induced in the conducting loop is given by = B l v , where l is the length of the side of the loop perpendicular to the velocity and B is the magnetic field. The induced current in the loop is I = R = B l v R , where R is the resistance of the loop. The magnetic force opposing the motion of the loop is F = I l B = ( B l v R ) l B = B^2 l^2 v R . To pull the loop at a speed v , the pulling agent must apply an external force equal in magnitude to the magnetic force. The power delivered by the pulling