Define electrostatic charge.
Electrostatic charge is an imbalance of positive and negative charges on the surface of an object, caused by the gain or loss of electrons.
Electrostatic charge is a type of electricity where the electric charge is stationary or “static,” meaning it is not moving or flowing
What happens when two objects are rubbed together in terms of electrostatic charge?
Electrons may transfer from one object to another making one object positively charged and the other object negatively charged causing the objects to attract.
Example: rubbing a balloon against a woollen jumper.
What is an electrical conductor?
A material through which charged particles can move easily, e.g. copper metal.
What is an electrical insulator?
A material that does not allow the movement of charged particles and prevents the charge being ‘lost’ to the surroundings as it passes through the wires. e.g. plastic that coats the wires.
What is electrical energy?
Produced when electric charges become separated and become in a state of excitement. Positive and negative charges try to get together causing the charges to flow continuously through a conductor due to a potential difference (voltage). (Charges are in motion causing an electrical current.)
Why are circuit diagrams used?
To represent a simplified version of a circuit. It helps in understanding how a circuit works and how it is built.
What is the difference between series and parallel circuits?
Series: Current goes through one globe then another; if one fails, all turn off. The current is always the same at all points in a series circuit. The lights share the voltage.
Parallel: Current splits between branches; if one fails, others still work. The current is split and the current going through each globe is added together for the total current coming from the power source. The lights don’t share the voltage.
Series circuits share voltage, while parallel circuits do not.
What is a short circuit?
A short circuit occurs when a current (moving electrons) flows along a different path from the one intended. Elecric charges will take the path of least resistance, which means that large currents can go in a short circuit, causing batteries to go out quickly. This can cause wires to heat up, damage, and even fires.
How does Ohm’s law relate current, voltage, and resistance?
When voltage is kept constant, current and resistance are inversely proportional. This means that doubling the resistance will halve the current or that halving the resistance will double the current.
V=IR
When do circuits not follow Ohm’s law?
When the relationship between voltage, current, and resistance is not constant, leading to non-ohmic circuits.
Give examples of non-ohmic circuits.
Filament lamps (light bulbs) and LEDs
Their resistance changes under different conditions.
What is Ohm’s law?
Is the relationship between current, voltage and resistance in a circuit.
When voltage is kept constant, current and resistance are inversely proportional. This means that doubling the resistance will halve the current or that halving the resistance will double the current.
V=IR
Recognize and draw correct symbols and conventions
Look at the slides :)
What does a Van De Graff do?
The van de Graaff generator produces an electrostatic charge by rubbing a belt. A van de Graaff generator is used to accelerate particles in X-ray machines, food sterilisers and process machines.
What is electricity?
“Electricity” is related to the presence and flow of an electric charge.
It is produced when negative electrons and positive protons are separated and reunite through a closed circuit.
What does a dry or wet cell do?
A dry cell (for example, a torch battery) or a wet cell (for example, a car battery) uses a chemical reaction to continually separate charges and produce current electricity through wires.
What is an electrical circuit?
A closed conducting pathway.
How does a circuit work?
As charged particles move around an electric circuit, they carry energy from the energy source (such as a battery) to the device that uses the energy (such as a light globe, motor or heater).
How do you know what is a conducter or an insulator?
Whether a material is a conductor or insulator depends on how easily they allow electrons to move through them (offer less or more resistance to the movement of charges.)
Can things change from being a conductor to an insulator?
Yes. Some substances, such as silicon, are insulators in their pure form but become conductors if they are combined with a small amount of another substance.
What is a semi-conductor?
Has an electrical conductivity value falling between that of a conductor insulator, such as glass.
What does a circuit need?
Electrical circuits require:
A power source
A conductor that when closed completes a circuit
A load that converts electrical energy into heat, light, movement …
What is a conventional current?
The current flows from positive to negative
What way does electrons flow to?
Electrons move from negative to positive
