Read the passage carefully and answer the following questions. Three specimens of magnetic material were tested using the apparatus shown in the diagram. When the switch is closed, the specimen picks up some of the iron nails but when the switch is opened, many or most of the nails fall off. The number of nails picked up and left on were found for three specimens. The table shows the results.

Which material is the best electromagnet among the three?

Explanation

Material Z has picked up largest number of nails when magnetic field is on and has retained least number of nails when field is off. So, it will be the best electromagnet.