Topic 11 - Static electricity Flashcards
Explain how an insulator can be charged by friction, through the transfer of electrons
When two insulators are rubbed together it can be charged by friction as electrons are transferred from one object to the other forming a positive charge on one object and a negative charge on the other.
What happens when a material gains/loses electrons?
A material that gains electrons becomes negatively charged and a material which loses electrons is left with a positive charge.
Like charges…? Unlike charges…?
like charges repel and unlike charges attract
Explain shocks from everyday objects in terms of movement of electrons
The build-up of electrostatic charge can cause sparking. This 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.
Explain lightning in terms of movement of electrons
Lightning is a form of sparking.
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).
Explain attraction by induction in terms of movement of electrons
Negative charge is induced on the part of the object closest to the charged object because positive charge of the charged object repels protons in the other object. They attract because opposite charges attract. (neg/pos switch based on example)
Explain how earthing removes excess charge by movement of electrons
Earthing is done by connecting the charged object to the Earth by a conductor.
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. They travel down and into the earth for a negatively charged object. This allows electrons to flow to the earth, removing excess charge. This allows materials to stay neutral.
Explain insecticide sprayers as an application of electrostatic charges
The insecticide is given an electrostatic charge so that the droplets of insecticide repel each other since they all have the same charge. This means that the insecticide is spread more evenly.
Describe some of the dangers of sparking in everyday situations
A build-up of static charge is a potential danger when fuelling vehicles. The friction between the fuel and the pipe causes the fuel t gain charge. The build-up of static charge can cause a spark to form which might ignite the fuel and cause an explosion.
Explain the use of earthing to prevent dangerous build-up of charge
Earthing can prevent dangerous build-up of charge if the fuel tank is connected to the earth with a bonding line during fuelling. This earths the vehicle by carrying the charge through to the earth which removes the risk of any sparks.
Define an electric field
An electric field is the region where an electric charge experiences a force.
Describe the shape and direction of the electric field around a point charge and between parallel plates
An electric field points away from positive charges and towards negative charges. They point to charges at right angles to the surface. The stronger the charge, the more field lines present and the stronger the force felt.
Parallel plates have a uniform field.
Explain how the concept of an electric field helps to explain the phenomena of static electricity
The object that is statically charged will generate an electric field. This field attracts the electrons on other objects causing a flow of charge resulting in sparks
