2.4 Current Electricity Flashcards
How is static electricity created?
When two electrically insulating materials are rubbed together electrons are rubbed off one material and deposited on the other
What happens to the material that gains electrons in static electricity?
It becomes negatively charged
What happens to the material that loses electrons in static electricity?
It becomes positively charged
What is the process of creating static electricity called?
Charging by friction
When two electrically charged objects are brought together what happens?
They exert a force on each other
What do two object with the same charge do?
Repel each other
What do two objects with opposite charges do?
They attract each other
The bigger the distance between electrically charge objects…
The weaker the force between them
What does a resistor do?
Reduces current flow
What does a variable resistor do?
Alter the amount of current continuously depending on the conditions
What does a thermistor do?
Changes the current flow as temperature changes
Does a voltmeter go in in series or parallel?
Parallel
Does a ammeter go in in series or parallel?
Series
What does a light dependent resistor do?
Changes the current depending on the light
What does a diode do?
Allows current to only flow in one direction
What is current?
It is the rate of flow of electrical charge through a current
What is the unit of flow of charge?
Coulombs
What is potential difference?
Voltage
The work done for every coulomb of charge flowing through the circuit
Which means the energy carried per electron
Current in a series circuit?
Same
Current in a parallel circuit?
Splits
Voltage in a parallel circuit?
Same
Voltage in a series circuit?
Splits
What is resistance?
The opposition to current flow
What is resistance measured in?
Ohms
What is ohms law shown on a graph?
If a resistor is kept at a constant temperature the current-voltage graph is... Directly proportional Passes through (0,0) As voltage doubles current doubles
What is ohms law in summary?
The current through a wire is proportional to the voltage across it provided the temperature remains constant
What is a component called that obeys ohms law?
An ohmic conductor
How do you work out the total resistance in a series circuit?
R1+R2+R3…. etc
Just add them
How do you work out the total resistance in a parallel circuit?
1/TR = 1/R1 + 1/R2 + 1/R3 … etc
What happens to the resistance in a filament bulb as a result of temperature?
Resistance increases as the temperature increases
Why does the temperature increase in a bulb with more current/voltage
The more energy there is for friction giving off heat
Because a diode only flows in one direction what is the resistance like in the other direction?
Very high
What does a diode need before current is produced?
A certain amount of voltage is needed before a current is produced
On a graph the line doesn’t start at the origin
But as voltage increases so does current
In a thermistor what will low temperature do to the resistance?
High resistance
In a thermistor what will a high temperature do to the resistance?
Low resistance
How does resistance link to light in an LDR?
Resistance decreases as light intensity increases
