What is an advantage of using an electromagnet rather than a regular magnet

Agas contained within a piston-cylinder assembly undergoes three processes in series: process 12: compression with pv= constant from 1 bar and 1 liter to 4 bar. process 23: constant pressure expansion to 1 liter. process 31: constant volume calculate the pressure and volume at each state, and sketch the processes on a p-vdiagram labeled with pressure and volume values at each numbered stat

What will a positive and a negative charge do if they are separated from each other?

Which articulations allow for greatest range of motion?