Question

Explain how energy losses in a transformer are reduced by having:

1. a soft-iron core.
2. a laminated core.

Answer 1

1. Soft iron is easily magnetized and easily demagnetized; this reduces heat loss due magnetization and demagnetization  (hysteresis loss) 
2. Laminated core increases resistance of the core which reduces the size of eddy currents thus reducing heating due to the eddy  currents.