Static Electricity Flashcards
Explain how an insulator can be charged by friction, through the transfer of electrons
When two insulators are rubbed together it produces friction. Electrons are transferred from one object to another. Forming a positive charge on one object and a negative charge on the other.
If conductors were rubbed, electrons will flow in/out of them cancelling out any effect.
Insulators become charged because the electrons cannot flow.
Explain common electrostatic phenomena in terms of movement of electrons
Sparking occurs when enough charge builds up, and the objects are close but not touching.
The spark is when the charges jump through the air from the highly negative object to the highly positive object, to balance out the charges.
Lightning occurs when the charge difference between the clouds and the earth becomes so great, and a massive spark (lightning) jumps across to balance the charges.
A positively charged balloon next to wall attracts in the wall. This induction causes the balloon to stick to the wall.
Comb charged induces the opposite charge in small pieces of paper, so picks them up.
Explain how earthing removes excess charge by movement of electrons
Earthing allows electrons to flow to the earth, removing excess charge and allows materials to stay neutral.
Explain some of the uses of electrostatic charges in everyday situations, including insecticide sprayers
They are sprayed from aircraft and given a charge. This means the spray droplets repel each other. So the droplets spread evenly, and are attracted to the earth. If not charged, there is a risk that some droplets will blow away or the spray will fall unevenly.
Describe some of the dangers of sparking in everyday situations, including fuelling cars
If charge builds up and a spark form when fuelling cars, it could ignite and cause a massive explosion.
o As fuel passes through a hose to the vehicle, a static charge can build up.
o When it is too large a spark might form.
o A resulting spark might ignite the fuel.
o The hoses are earthed to stop this occurring.
Define an electric field
If charge builds up and a spark form when fuelling cars, it could ignite and cause a massive explosion.
o As fuel passes through a hose to the vehicle, a static charge can build up.
o When it is too large a spark might form.
o A resulting spark might ignite the fuel.
o The hoses are earthed to stop this occurring.
Forces exerted:
The charged objects experience a force – electrostatic force of attraction/repulsion.
o Greater charge = greater force
o Closer together = greater force (force is proportional to the inverse square of the distance).
o It is a noncontact force, as force can be felt even when the objects are not touching.
Describe the shape and direction of the electric field around a point charge and between parallel plates
Like magnetic fields for magnets, electrical fields are for charges.
An electric field is the region where an electric charge experiences a force. They point in the direction a positive charge would go and to charges at right angles to the surface.
Stronger the charge, the more field lines present and the stronger the force felt.
Parallel plates have a uniform field.
