Teacher:In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
Teacher: Now, understand the problem? Solve this instance: What is opposite of often?, Context: Operating at normal power line frequencies, universal motors are often found in a range less than 1000 watts. Universal motors also formed the basis of the traditional railway traction motor in electric railways. In this application, the use of AC to power a motor originally designed to run on DC would lead to efficiency losses due to eddy current heating of their magnetic components, particularly the motor field pole-pieces that, for DC, would have used solid (un-laminated) iron and they are now rarely used.
Student:
rarely