Electrostatics Flashcards
What happens when you put two north pole magnets together
They repel
In which direction does current flow
Positive to negative
In what direction does friction occur
In opposite motion
We……..remove protons from a particle (easily)
Cannot
Negative electrons can easily move through……………and can be rubbed off atoms by………..
Conductors
Friction
Describe what’s happening when you charge with friction (with a cloth and rod).
When rubbed the electrons from the cloth are transferred to the cloth.
This makes the rod negatively charged and the cloth positively charged
Both materials are insulators, so the charge can not flow away. A metal cannot be charged this way.
Define the centre of gravity
Point where a mass of object acts
How do you charge by induction (with a balloon)
The balloon is charged by friction
The orbiting electrons in the wall are attracted by the positive charge of the balloon, so they orbit towards it.
This makes the surface negatively charged
How does a Van de Graaff Generator work
Metal comb pulls off electrons from rubber belt by friction
the electrons are transferred to the top of the dome, causing the surface to become negatively charged
Give some dangers of electrostatic forces
A build up of static charge can produce sparks if a conductor e.g ground or a person is nearby
This is dangerous if there is flammable material round e.g fuel
To prevent a build up of charge an object should be:
- made of metal
- connected to the earth via a metal strip
This is called ‘earthing’.
Give 4 uses of electrostatics
Paint spraying
Photocopiers
Participators
Inkjet printer
How does paint spraying work
The paint droplets fan out because they repel each other. This gives an even paint coverage.
The paint is attracted by the opposite charged objects so that shaded areas are covered
How do photocopiers work (7)
The original is placed on the photocopier
The rotating drum inside becomes charged
Light reflects from the original to the drum
The drum looses charge in areas where the light touches
Toner is attracted to the charged areas of the drum
Toner is transferred from the drum to the sheet of paper
Toner is fussed to the pair by heating and a copy is ready
How does a participator work
Smoke + waste gas passes through a charged metal grid
They rub and become charged too
They are attracted to the oppositely charged collecting plate and stick
The plates are cleaned periodically
Pollutants are becoming charged not gasses.
How does an inkjet printer work
Tiny ink droplets are projected by the charge onto two metal plates
Varying the p.d changes the position of ink on the page.
