Electricity Flashcards
Relationship between power, current and voltage
P = I x V
Relationship between energy transferred, current, voltage and time
E = I x V x t
Relationship between voltage, current and resistance
V = I x R
Relationship between charge, current and time
Q = I x t
Relationship between energy transferred, charge and voltage
E = Q x V
What is voltage
Energy transferred per unit charge passed
The volt is a joule per coulomb
What is electric current in solid metallic conductors
A flow of negatively charged electrons
What is current
The rate of flow of charge
Current and voltage in a series circuit
Current - constant
Voltage - splits
Current and voltage in a parallel circuit
Current - splits
Voltage - constant
What is direct current
Voltage is constant
Charges move in one direction at a constant rate
Oscillope shows horizontal line
What is an alternating current
Voltage oscillates, we set the amplitude
Charges oscillate and move back and forth (not changing direction)
Oscillope shows sine wave
Why do we wire our homes with parallel circuits
- if one component fails the rest keep working
- same voltage for every appliance
- each appliance can have different currents
what are LDRs
Light dependent resistors
Resistance changes with light
High resistance in dark and vice versa
They are used to control a circuit eg alarms
