Current & Voltage Flashcards
What is a diode and how does current flow through it?
A diode is a component which only allows energy to flow through in ONE direction
Why does an increase in temperature reduce the current?
The heat makes the particles vibrate more which makes it harder for the electrons to flow through, reducing the current
What is a LDR? How does current flow through it and how may they be used?
LDR’s are light dependant resistors. The resistance increases as the light increases.
Useful for street lights
What is a thermistor? How does current flow through it and where may it be used?
Thermistors are resistors which are affected by temperature. The resistance decreases as the temp increases
Can be used in fridges
How does resistance affect the current?
The higher the resistance the lower the current
How can you work out the total resistance in a circuit?
Add up the resistance of all individual components
What are the rules for current in a series circuit?
Current is the same
What are the rules for potential difference in a series circuit?
Voltage is shared between components
What are the rules for current in a parallel circuit?
Current is shared between different branches
What are the rules for potential difference in a parallel circuit?
Voltage is the same in each branch
What is the difference between alternating and direct current supplies?
Alternating current is constantly changing direction
Direct current does not change direction
What is an electrical cabel made from?
Why is each material used?
The cabel is made from copper which is a good conductor
Plastics for the cover which is a good insulator
What is the purpose of a fuse and how does it work?
A fuse is designed to increase the safety of an electrical appliance
Why are appliances with a metal case usually ‘earthed’
If the earth wire touches the side of the metal case then someone could get electrocuted
So the earth wire prevents electrocution by providing an easier route for the electrons
How should the size of fuse in a plug be determined?
The fuse should allow a slightly higher current than appliance demands
