Have you every thought that what does the small cylinder on Laptops charger contain or what is its purpose? Then your answer will be definitely no.
You find this small cylinder in Laptop charger, other chargers, mouse or Keyboard’s wire. We see it everyday but never thought to open it and see what is inside. So let me tell you that there is no wire or circuit in this cylinder. It only contains two magnets which control electromagnetic waves.
When electricity is passed through any wire it creates electromagnetic interference while the wire already contains electromagnetic waves because of which near the electricity output this cylinder is made which blocks electromagnetic waves and protect your wire and your hardware you use with them.