Figure 2115 In Figure 2115 a straight wire carries a current

Figure 21.15 In Figure 21.15, a straight wire carries a current I. The wire passes through the center of a toroidal coil. The current is quickly reduced to zero. The induced current through the resistor R is: A) from a to b B) zero C) from b to a

Solution

The current in the center wire is into the page. Use the Ampere’s right hand rule, the magnetic field is clockwise direction along the rim of the toroidal coil. Due to this magnetic field, there is induced current in the coil from b to a.

Hence, the induced current through the resistor R is from b to a. So, the correct option is (C).