Here are the three concepts you need.
The magnetic flux is equal to the magnetic field times the area the field passes through flux = B*A
The induced EMF is equal to the change in flux over time EMF = d(flux)/dt
The induced current is equal to the EMF divided by the resistance. I = EMF/R
Since the B field is constant you therefor have to figure out dA/dt. How is the area changing with time. I think it is a simple as Afinal - Ainitial divided by 0.1 s.
Now EMF = B*(Afinal - Ainitial)/0.1 s
Divide that by the resistance and you should have your current.