Problem 7 Consider a sliding rail problem where the conductive rails expand as they progress in the y direction as shown. If w=10cm and the distance between the rails increases at the rate of 1.0cm in the x direction per 1.0cm in the y direction, and u_(y)=2.0m//s, find the V_(emf) across a 100-Omega resistor at the instant when y=10cm if the field is (a) B_(0)=100 mT and (b) B_(0)=100 cos(20 t)mT. Answer: (a) (b) 0.03 sin(20 t)+cdots Volts .