Chapter 21 - Electromagnetic Induction and Faraday's Law - Problems - Page 620: 8

a. Counterclockwise b. Clockwise

a. Call the flux through the smaller loop positive when magnetic field is pointing out of the page. The initial magnetic field through the small loop is out of the page and the flux is positive. If the resistance is increased, the current in the outer loop decreases, and thus the flux through the smaller loop decreases. To oppose this change, the flux produced by the induced current must also be positive, i.e., the induced field points out of the page. By the right hand rule, induced current circles counterclockwise to create such a field. b. If the smaller loop is placed to the left, then the initial magnetic field through the small loop is into the page and the flux is negative. If the resistance is increased, the current in the outer loop decreases, and thus the flux through the smaller loop becomes less negative. To oppose this change, the flux produced by the induced current must be negative, i.e., the induced field points into the page. By the right hand rule, induced current circles clockwise to create such a field.