Current Electricity Flashcards
What is current electricity
Current electricity is the result of electrical charge on the move.
What are free electrons
Free electrons are negative electrons that carry charge
What is a closed circuit
A closed circuit is a circuit that has a continuous pathway between the terminals of the power supply
What is current caused by
Negative electron flow from the negative to the positive terminal of the power supply
What materials are usually conductors
Metals
Give the free electron explanation of conductors and insulators
Metals have a regular lattice structure of ions and a cloud of delocalised electrons
free electrons will drift in the direction of a positive terminal
Non metals lack free electrons and are locked in the bonding process and can’t conduct
What is the current in a series circuit
Always the same
Charge is not lost but energy is converted
The current leaving the supply is equal to the current returning
What is the current in a parallel circuit
The current will divide at junctions and recombines but is always conserved
What is the difference between electron flow and conventional current flow
Conventional goes for positive to negative while electron flow is in the opposite direction
What is electric charge measured in
Coulombs
Give the definition of current
The rate of flow of charge
Define what one coulomb is
The charge passing any point in a circuit when a steady current of one ampere flows for one second
What is the formula for charge
Charge = current divided by time
How many mA in one amp
1000
How many volts in one KV
1000v
What is potential difference
Commonly known as as voltage
What is the formula for potential difference
Voltage = energy divided by charge
What does ohms law state
The current through a wire is directly proportional to the voltage across it as long as the temperature remains constant
What is the formula for ohms law
Voltage= current x resistance
What is the free electron explanation for resistance
The opposition to electron flow is caused by collision with the atomic lattice and other electrons
Higher the collisions the higher the resistance
Each collision transfers energy to the atom causing it to vibrate producing heat
How does the length and area of a wire effect the resistance
Short thick wires have low resistance
Long thin wires have high resistance
How does the length and area of a wire effect the resistance
Short thick wires have low resistance
Long thin wires have high resistance
