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What is static electricity?
Static electricity is an imbalance of electric charges within or on the surface of insulating materials.
What subatomic particle(s) can be transferred between atoms?
Only the electrons.
Why can’t static electricity work with conducting materials?
The friction that usually causes electrons to move from one object to the other and then build up charge wouldn’t work because the electrons would just flow straight back again.
When electrons are transferred between atoms, which ones are charged positively and negatively?
The atoms that lose electrons will be positive, while the atoms that gain electrons will be negative.
What happens when, using a dry cloth, you rub a polythene rod vs a perspex rod?
The polythene rod transfers electrons to the surface atoms of the rod from the cloth, and it becomes negatively charged. The perspex rod transfers electrons from the surface atoms of the rod onto the cloth, and it becomes positively charged.
How can static electricity cause sparks?
If two objects are oppositely charged, electrons in the air molecules between the two objects experience a force towards the positive object. If the electric field is too strong, sparking happens because some electrons are pulled out of air molecules by the force of the field. These electrons hit other air molecules and knock electrons out of them, creating a sudden flow of electrons between the two charged objects.
How do induced charges work?
A charged object, when in close proximity to another, will repel “like” charges, leaving excess unlike charges near it. (if the charged object is negatively charged, electrons will be repelled, leaving immobile, positively charged protons) These nearby unlike charges are attracted more strongly than the distant like charges.
For electric fields, which way do the field lines point?
They always point from the positive to negative charge, i.e. a positive electric field will have field lines pointing outwards, while a negative electric field will have field lines point inwards.
How does the distance from the charged particle affect the strength of the electric field?
The electric field is stronger the closer you are to the charged particle.
What happens to air if a strongly charged object ionises it?
The air particles will lose some of their electrons, and is able to conduct electricity.
What is the difference between a cell and a battery?
A cell is a single device that converts chemical energy into electrical energy, while a battery is a collection of cells that provide a steady source of electrical energy. A battery also provides a higher voltage and more energy than a single cell.
What does a fuse do?
A fuse contains a thin piece of wire that melts when too much current passes through it. This breaks the circuit, which stops the flow of current and reduces the risk of fire or electrocution.
What is a thermistor and how does it function?
A thermistor is a type of resistor that is dependent on temperature/heat. Its resistance decreases when the temperature increases, unlike regular resistors.
What does a light-emitting diode (LED) do?
It emits light when current flows through it, and - because it is a diode - it only allows current to flow in one direction.
Which way does current flow conventionally from one terminal of a battery/cell to the other?
From the positive to the negative terminal. (even though in reality, the electrons do the opposite)
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