Electricity Flashcards
What is Ohm’s law?
Voltage = current x resistance
1 volt =
1 volt = 1 joule per coulomb of charge moved
Voltage is the…
Voltage is the work done per unit charge moved
Charge =
Charge = current x time
Current through ohmic conductor is directly proportional to…
Current through ohmic conductor is directly proportional to potential difference across it
Resistivity =
Resistivity = (resistance x cross-sectional area) / length
Area of a circle =
Area of a circle = pi x r squared
Power =
Power = energy / time
Power in electrical circuits =
Power in electrical circuits = voltage x current
Energy transferred =
Energy transferred - power x time
Define current
Rate of flow of charge
What is 1 coulomb
The amount of current that passes in 1 sec if the current is 1 amp
What is the property of an ohmic conductor
Current through it is proportional to the pd across it, providing external conditions are constant
What are NTC thermistors
Negative temp coefficient, where resistance falls and temperature rises
What are diodes designed to do
Limit the current flow to one direction
Define resistivity
The resistance of a 1m length with a 1m² cross-sectional area
What is resistivity measured in
Ohm-metres
2 uses of superconductors
Power cables to transmit energy without losing power
Electrical circuits with no resistance
What is a superconductor and how it it created
A material without any resistance, formed by cooling a material below its transition temp, causing resistivity to disappear
Define power
The rate of energy transfer (energy/time)
What effect on the resistance of an LDR does increasing the light intensity have
LDR resistance falls
Define EMF
The amount of electrical energy battery produces per each coulomb of charge
Why do batteries have internal resistance
In a battery, chemical energy makes electrons move. As they move, they collide with atoms in the battery which causes resistance
Total resistance of a series circuit =
R1 + R2 + R3
Total resitsance in a parallel circuit =
1/R1 + 1/R2 +1/R3
What is a potential divider at its simplest
Resistors in series with a voltage source which splits the voltage in the ratio of the resistances
Energy =
charge x voltage
Relationship between power, force and velocity
Power = force x velocity
