A rectangular loop of copper wire of resistance r has width a and length

b. the loop is stationary in a uniform magnetic field. the magnetic field b at time t = 0 seconds is directed into the page as shown below. the uniform magnetic field varies with time t according to the relationship b = b0 cos ω t, where ω and b0 are positive constants and b is positive when the field is directed into the page. the direction of the induced current in the loop when ω t = π 2 , after the magnetic field begins to oscillate is