Topic 3 Electricity Flashcards
What type of charges are there?
Negative and positive
What type of charges does Perspex have?
Positive
What type of charge does polythene have?
Negative charge
What do like charges do?
Like charges repel each other
What do unlike charges do?
Opposite charges attract each other
How does attraction occur?
When a charged object is brought near an uncharged object or also when two objects of opposite charges are near each other
What are the units for charge?
Coulombs sign C
Evaluate the charges of neutral,positive and negative.
A neutral material has the same number of positive and negative charges.
A positive material has extra positive charges.
A negative material has extra negative charges.
What happens if we rub a polythene with a cloth and a Perspex with a cloth?
Polythene and cloth: The cloth looses electrons becoming positive and the electrons go on the polythene becoming negative
Perspex and cloth: The electrons move from the Perspex to the cloth. The Perspex becomes positively charged and the cloth becomes negatively charged
What happens when a rubbed plastic ruler is brought near tiny pieces of paper?
The tiny pieces of paper are attracted towards the ruler.
Flashcard
What is resistance?
The opposition to current flow in a conductor.
What is the effect of length on resistance?
The longer the wire, the higher the resistance.
What is the effect of diameter on resistance ?
The thicker the wire, the lower the resistance.
What is the effect of temperature on resistance?
The higher the temperature, the higher the resistance.
How does the type of material affect resistance?
A good conductor has less resistance, while a bad conductor has more resistance.
What is stored in a battery (cell)?
Chemical energy
What happens when a battery is connected to a closed circuit?
Some of the chemical energy is converted into electrical energy (current flows), and some is converted into heat (wires heat up).
What does a battery do in a circuit?
A battery has the ability to make the charge flow through the conductor (wire).
What is the e.m.f. (electro-motive force) of a battery?
It is the energy used to drive 1 coulomb around a complete circuit. For example, a 12V battery has an e.m.f. of 12V, meaning it uses 12J of energy to drive 1C around the circuit.
What is the equation relating electrical energy, charge, and voltage?
Electrical Energy = Charge × Voltage, or E = Q x V.
What is electrical energy?
Electrical energy is the movement of electrons in a material.
Where do the electrons come from, and how do they move?
Electrons are found in the outer part of the atom of every material. In conductors (e.g., metals), electrons can move if supplied with energy.
What is the standard unit of electric current?
The standard unit is the Ampere (A), but it can also be measured in milliampere (mA).
