Examples of Static Electricity (Edexcel GCSE Physics)

• Common electrostatic phenomena include:
  • Shocks from everyday objects
  • Lightning
  • A charged balloon sticking to a wall
  • Charged comb picking up small pieces of paper

Shocks From Everyday Objects

• The build-up of electrostatic charge can be quite dangerous and can cause sparking (also known as an electric shock)
• A static electric spark occurs when:
  • Two objects are charged by friction
  • They become oppositely charged
  • The large surplus of electrons causes electrons to 'jump' across to an object that is neutral

• Since a current is the flow of electrons, this causes a small current to flow between the objects, called a spark
• An example of sparking is the small electric shock felt from touching a door handle, or another person, after walking on a vinyl floor or nylon carpet with rubber shoes or socks
  • Sparks can become quite dangerous and can cause a fire by igniting flammable gases and liquids, such as petrol

Examples of sparking from touching a door handle or another person

Lightning

• In a storm, clouds move over each other
  • This causes them to become charged when electrons are transferred between them

• Since the ground is neutral, the negative charges from the cloud jump to meet the positive charges on the ground creating a giant spark (a current from a transfer of charge)
  • This phenomenon is known as lightning

Lightning is caused by the build-up of charge in clouds

Sticking a Balloon to the Wall

• Rubbing a balloon on a woollen jumper transfers electrons onto the balloon by friction
• The balloon is now negatively charged whilst the jumper is left positively charged
• The wall is still neutral, however, when the balloon is placed near the wall, the negative electrons in the wall are repelled by the negative balloon
  • This leaves a region of wall with a net positive charge
• Since opposite charges attract, the balloon sticks to the wall from only the electrostatic attraction

Charged Comb Picking up Paper

• Static electricity can be observed when running a plastic comb through hair then placing the comb near small pieces of paper
  • The pieces of paper can be observed to jump up and stick to the comb

• The comb becomes charged by friction from the hair so it is left with a negative charge as the electrons are transferred to it
  • This also means the hair strands become positively charged and they begin to repel each other

• Pieces of paper are neutral but as the comb comes close to them, the positive charges are brought to the surface of the paper and are attracted to the negative charges on the comb
  • Therefore, the papers 'stick' to the comb through static electricity

A negatively charged comb can attract small pieces of paper

• Earthing this is the process of removing excess charge by the movement of electrons
  • This is used when an object or body is charged and the charge needs to be removed to avoid sparking
  • It is sometimes called grounding

• The Earth can be imagined to be a giant reservoir of electrons, so it can give and take excess electrons
• Earthing is done by connecting the charged object to the Earth by a conductor
  • A conductor is used since charge can flow through it, unlike an insulator

• If a positively charged object is connected, electrons will be attracted up through the conductor and to the positive charge, cancelling them out
  • This is because opposite charges attract

A positively charged object when earthed will move electrons up the conductor

• If a negatively charged object is connected to the earth, electrons travel down the conductor and into the earth
  • This is because like charges repel

A negatively charged object when earthed will move electrons down the conductor