Static electricity

Scenario

  • Sometimes you walk on the carpet… and maybe rub your leg against the carpet.

  • And you touch the doorknob… OUCH!

  • That little static felt is called static electricity.

Definition

  • Static electricity comes from 2 parts → Static: The build up of the electrons

  • Electricity → The little shock

  • Friction causes the transfer of electrons

  • Only electrons can travel, never protons.

→ Negative charge = Object with more electrons than needed

→ Positive charge = Object with less electrons than needed

→ Neutral charge = Object with neutral charge

Examples

  • Well static electricity happens because the object wants to balance itself…

  • By removing it electrons

  • Let’s use our example from earlier

  • Leg rubs against the carpet → Electrons accumulate in the body, making it a negative charge

  • Electrons are waiting to get balanced

  • Doorknob touched → Electrons transfer to doorknob due to metal being conductor

  • Remember: Air is an insulator

  • But in this situation, charge is too strong for air

  • So air temporarily becomes conductor because electrons rip through air molecules

  • And electricity happens due to travel of electrons

Travoltage rubs leg against carpetSo may electrons! Electrons are waiting to balance itselfTravoltage gets near doorknob, and electrons travel to the doorknob through the air (air temporarily becomes conductor)

Remember that air is an insulator, but it can become a conductor if electrons rip through it.

Triboelectric chart

  • The reason why you get more static in the winter in generally because some electrons are lost to humidity in summer

  • But in winter, it’s barely humid, so the electrons don’t escape as easily

Well, we know 2 negatively charged objects repel, and 2 objects with the opposite charge attract.

What happens when you put a negatively/positively charged objects, something weird happens. The neutral object.. attracts?

Paper and balloon attract

  • When a negative object gets near a neutral object, the electrons move because of them repelling

  • Same charged objects repel, so when an electron gets near another electron, the electrons move away

  • This creates a space of protons

  • Electrons and protons are attracted to each other

  • So the electrons stick to that space of protons

  • This is called “polarization”

  • An example of this is the balloon and paper. The balloon is rubbed against the sweater (assumption). The paper cannot lose electrons.

  • Now, the balloon is near the paper. The paper’s electrons moved away from the balloon’s electrons. This creates a space of protons on the paper

  • And the balloon attracts to the paper

Visual example

  • Look, the balloon has a lots of electrons

  • So does the wall. The wall has a neutral charge

  • The electrons moved in the wall

  • There’s a space of protons

  • The balloon sticks to the wall