Electricity Flashcards
How do you work out resistance in parallel
1/R =1/R1+1/R2
What happens if you put cells in parallel
They will deliver the same potential difference as one
What an advantage of using cells in parallel
They will last longer
What is an ohmic conductor
A component that’s potential difference is directly proportional to the current at a constant temperature
Why is a filament bulbs I/v graph the shape it is
-as the current flows is gets hotter
-therefore there is more resistance
-therefore the increase in current starts to slow down
It reaches a maximum when the resistance is a maximum
How can you make sure that measuring resistance of a wire is accurate
Use a low current to reduce resistance and heat loss
What is the resistance of an ammeter
Zero
What is the resistance of a volt meter
Infinity
What do you need to measure to find resistivity p=RA/L
The length, diameter and resistance
What can be the problems during experiments for resistivity
Kinks in the wire
Not having a constant diameter
High resistance between crocodile clips and the wire
What is superconductivity
When a material has no resistance, due to being cooked down below its transition temperature.
What are uses of superconductivity
For power cables
Strong magnets
Trains
What is internal resistance
The loss of potential difference per unit of current in the power souce
What is terminal potential difference
The potential difference of everything in the circuit except the cell
What is a potential divider
A combination of resistors in series connected across a voltage source to produce a split in potential difference
