How to separate a mixture of iron ad copper pieces using an electromagent

Imagine you had to physically add electrons, one at a time, to a previously neutral conductor. you add one electron very easily, but the second electron requires more work. in your initial post to the discussion, explain why this is. also, what happens to the work needed to add the third, fourth, fifth, and subsequent electrons

In positive numbers less than 1, the zeros between the decimal point and a non-zero number are blank significant

What are the north and south poles of a solenoid change with?