P2- Electricity Flashcards
What is unit of current
Ampere (A)
What is unit of potential difference
Volt (V)
What is unit of resistance
Ohm
In a single closed loop what happens to the current
Has the same value everywhere in circuit
What is potential difference
Is the driving force that pushes the charge around
What is resistance
Anything in the circuit that slows the flow down
Equation linking potential difference and resistance
P.d = current times resistance
What is the I-V characteristics for an ohmic conductor
Current through an ohmic conductor is directionally proportional to potential difference
Straight line
What is the I-V characteristics for filament lamp
As current increases, the temp of the filament increases, so resistance increases
Graph gets shallower
Curve
What is the I-V characteristics for a diode
Only flows through a diode in one direction
Very high resistance in reverse direction
What are series circuits
Connected in a line, end to end between the +ve and -ve of the power supply
What happens in a series circuit
Cell potential difference adds up
Total potential difference is shared
Current is the same everywhere
Resistance adds up
What are parallel circuits
In parallel circuits, each component is separately connected to the +ve and -ve of the supply
What happens in parallel circuits
P.d is the same across all components
Current is shared between branches
Adding a resistor in parallel reduces total resistance
In a series circuit what happens if you remove or disconnect one component
Circuit is broken and they all stop
In a parallel circuit what happens if you remove or disconnect one of them
It will hardly affect the others at all
What colour is live wire
Brown
What colour is earth wire
Green and yellow
What colour is neutral wire
Blue
What wire produces the potential difference of 230v
Live wire
What two wires produces the potential difference of 0V
Earth wire
Neutral wire
What is the order of the national grid
Power station
Step-up transformer
Step-down transformer
Consumers
What happens to the potential difference when using a step-up transformer
Potential difference is increased
What happens to the potential difference when using a step-down transformer
Potential difference is reduced again
