Topic 2 Flashcards
(18 cards)
What does a step up transformer do
Increase the voltage
What does a step down transformer do?
Decreases the voltage
How does temperature affect resistance?
As temp increases the atoms in the wire vibrate causing the resistance to increase
What is the role of a diode?
To control the direction of current
How does an increase in resistance affect current?
Causes rhe current to decrease
What is the role of an ammeter
Measure the current
What the color of the earth wire
Green and yellow stripes
What is the color of the live wire?
Brown
What is the color of the neutral wire
Blue
What does the earth wire do?
If the live wire breaks in runs the current into the ground so that if some one touches the live wire they will be safe from electrocution
What does friction do?
Causes kinetic energy to be transferred to heat energy
When is a step up transformer used?
When going from a power station to the mains electricity
When is a step down transformer used
When going from mains electricity to homes
What is the role of a fuse?
It melts if the circuit gets too hot
This breaks the circuit
Allowing it to cool down
How do you measure the voltage around a lamp
The voltmeter should be in parallel to the lamp (beneath)
It must be connected to the circuit in two places (before and after the lamp)
How do you draw an ammeter in a circuit?
It should be in series to the other components (in the same circuit)
Why is a high potiential difference used in mains electricity
So power transmission is faster
Why does the resistance increase as lamps are added in parallel?
There are more pathways for the electrons to flow through
Therefore they can flow faster
(Think of people trying to walk through a hallway)
