A horizontal loop abcd is moved across the pole pieces of a magnet as shown in fig. with a constant speed v. When the edge ab of the loop enters the pole pieces at time t = 0 sec. Which one of the following graphs represents correctly the induced emf in the coil

When loop enters in field between the pole pieces, flux linked with the coil first increases (constantly) so a constant emf induces, when coil entered completely within the field, no flux change so e=0.
When coil exit out, flux linked with the coil decreases, hence again emf induces, but in opposite direction.