Static Electricity (AQA GCSE Physics): Flashcards
Exam code: 8463
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Define non-contact force.
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Cards in this collection (30)
Define non-contact force.
A non-contact force is a force that acts on an object without it being physically in contact with it.
What are the three types of charge a particle can have?
Positive, negative and neutral (no charge).
State the charge of an electron, a proton and a neutron.
An electron is negative, a proton is positive and a neutron is neutral (no charge).
In a neutral atom, the number of electrons is ______ the number of protons, so the equal but opposite charges cancel out.
In a neutral atom, the number of electrons is equal to the number of protons, so the equal but opposite charges cancel out.
What happens when two charged objects are brought close together?
If the charges are opposite, the objects attract (move closer together). If the charges are the same, the objects repel (move further apart).
True or False?
An object becomes positively charged because it gains positive charge.
False.
An object becomes positively charged because it loses electrons, not because it gains positive charge.
Define charging by friction.
Charging by friction is when certain insulating materials become electrically charged by being rubbed against each other, with one gaining a net positive charge and the other a net negative charge.
When an acetate rod is rubbed with a cloth, which object gains electrons and which loses them?
The cloth gains electrons and becomes negatively charged; the rod loses electrons and becomes positively charged.
When a polythene rod is rubbed with a cloth, electrons are transferred from the cloth to the rod, so the rod gains a ______ charge and the cloth gains a positive charge.
When a polythene rod is rubbed with a cloth, electrons are transferred from the cloth to the rod, so the rod gains a negative charge and the cloth gains a positive charge.
Define static electricity.
Static electricity is caused by a build-up of stationary charge on the surface of an insulator.
Give three everyday examples of static electricity.
Any three from: dust particles accumulating on surfaces, hair sticking up after combing with a plastic comb or going down a plastic slide, a rubbed balloon sticking to a wall, sparking.
Why does a balloon stick to a wall after being rubbed on a woolly jumper?
Rubbing transfers electrons onto the balloon, making it negatively charged. When placed near the wall, the balloon's electrons repel the wall's electrons and attract the wall's positive charges, so the balloon sticks.
What two conditions lead to a spark occurring between two objects?
There must be a large potential difference between the two objects, which causes a current to flow between them.
Why does an electric shock usually travel through an earthed copper wire rather than through a person touching it?
Current always takes the path of lower resistance. Since copper has a lower resistance than a person, the current flows through the copper wire to Earth instead of through the person.
Explain how a thundercloud builds up charge during a storm, leading to lightning.
Ice crystals in the cloud rub together, transferring electrons. The top of the cloud becomes positively charged and the bottom becomes negatively charged, building up a large potential difference between the cloud and the ground until a large spark discharges.
How does a bonding line reduce the risk of sparking when refuelling an aeroplane?
The bonding line earths the aeroplane, carrying any excess charge that builds up from friction as fuel passes through the pipe safely to the Earth, removing the risk of a spark.
True or False?
Static electricity is caused by charge moving through a conductor.
False.
Static electricity is caused by a build-up of stationary charge on the surface of an insulator; it is normal electricity that involves charge moving through a conductor.
What is created around a charged object?
A charged object creates an electric field around itself.
Electric field lines always point away from ______ charges and towards negative charges.
Electric field lines always point away from positive charges and towards negative charges.
How does field strength change with distance from a charged object, and how is this shown on a field diagram?
The field is strongest close to the object, shown by the field lines being closer together, and weaker further away, shown by the lines being further apart.
What determines whether the force between two charges is attractive or repulsive?
If the charges are the same (both positive or both negative), the force is repulsive. If the charges are opposite, the force is attractive.
How does the size of the electrostatic force between two charged objects change as the distance between them changes?
The force gets stronger as the distance decreases and weaker as the distance increases. This applies to both attractive and repulsive forces.
True or False?
Two negative charges brought close together have a weaker repulsive force than if they were far apart.
False.
Bringing the charges closer together makes the repulsive force stronger, since the force is stronger at shorter distances.
Define electric field.
An electric field is a region in which a charged object experiences an electric force.
In which direction do electric field lines always point?
From positive to negative.
Describe the electric field line pattern for an isolated charged sphere.
For a positive sphere, the field lines point away from the centre. For a negative sphere, the field lines point towards the centre.
The electric field between two parallel plates is a ______ field, made up of straight parallel lines from positive to negative.
The electric field between two parallel plates is a uniform field, made up of straight parallel lines from positive to negative.
Why is the electric field a useful concept for explaining the non-contact force between charged objects?
The electric field cannot be seen, but it can be detected by another charged object, which experiences an electric force when it moves within that field, without the objects touching.
What happens if an electric field becomes strong enough?
The charges are forced through insulators such as air, creating a spark.
True or False?
Field lines between two parallel plates are curved.
False.
They are straight, parallel lines from positive to negative.
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