Electric Charge (electrostatic) Flashcards
What are electrical insulators (+ examples)
Materials that don’t conduct electricity
E.g. Plastic, hair, jumper
What are electrical conductors (+ examples)
Materials that conduct electricity
E.g. Metals
What causes insulating materials to be charged
Friction
How do insulating materials get charged using the example of hair and a balloon
Rubbing hair and the balloon together causes electrons to transfer from one object to another so one object (the hair) is positively charged and the other object (the balloon) becomes negatively charged
Why does the hair stand on end after being rubbed by the balloon
The hair and the balloon are oppositely charged so the hair is trying to get as close to the hair as possible as opposite charged attract
The hairs are the same charge so they try to repel against each other and get as far away from each other as possible
Why would the hair and balloon stick together after rubbing on each other
The hair is positively charged and the balloon is negatively charged so they stick together as opposite charges attract
What does a neutral object have
Equal amounts of positive and negative changes on it
What do charged objects have? Why?
There is an imbalance of positives and negatives. This is because the object has lost or gained electrons
What needs to happen to rebalance the charge
Have to neutralise the object by either restoring electrons or removing electrons
How do we neutralise an object? What is the process?
Earthing/ grounding
Connecting the charged object with a conductor (as it lets electrons flow along it easily) to a large source of electrons, usually the ground.
What happens when neutralising a positive object
The electrons from the ground flow to the positive object so it gains electrons and becomes neutral
What happens when neutralising a negative object
The electrons from the object flow to the ground so it loses electrons and becomes neutral
What is polarisation
The separation of positive and negative charges in an overall neutral object. This object is said to be polarised
What happens to the charges in a wall as a negatively charged balloon moves towards it
The negative balloon is attracted to the positive charges in the wall. The negative electrons in the wall repel against the negative balloon so the charges in the wall separate making the wall polarised
Why might it be dangerous to refuel a plane and what can be done to prevent the dangers
Friction between the air molecules and the plane causes the plane to be charged. The charged plane could cause an explosion when refuelling
To prevent this we need to ground the plane by connecting the plane with the ground with a conductor so the charge can be neutralised
Why might it be dangerous to fill a a storage tank with fuel and how can we prevent this
The friction between the fuel and the fuel pipe causes the tanker to become charged. The charged tanker could cause an explosion
To prevent this we need to ground the tanker by connecting it with a conductor to the ground to neutralise it
What is a use of electrostatic charges and how does it work (5 steps)
Photocopiers
In the photocopier a light sensitive plate is negatively charged
An image of the document projects onto the plate, the bright areas lose their charge and the dark areas keep it
Positive powdered ink is attracted to the dark areas which were still negative
A blank sheet of paper is pressed against the plate and picks up the powered ink
The paper is heated so the powered ink melts and sticks to the paper
