Electricity Flashcards
How does a cell work, with reference to energy
Cell contains chemical energy, which is transfers to electrons
What do electrons do in the circuit
They move through wires to transfer energy to the components of the cell
What direction does charge flow
+ve —> -ve
What direction do electrons flow, with reference to charge
Opposite direction to charge flow
Define voltage
Measure of how much energy is transferred to/by each unit (coulomb) of charge
How much energy would a 6V battery transfer
6J to each coulomb of charge
What is the equation for energy transferred in circuit
E = Q V
How are voltmeters connected in the circuit
In parallel
Define current
Rare of flow of charge (how many coulombs pass per second)
What is the equation for charge
Q = I t
How are ammeters connected in the circuit
In series
Define resistance
Measure of how much a component resists the flow of charge
How would you describe a fixed resistor
Ohmic
How are current and pd related in a fixed resistor
Current and pd are directly proportional
How is a fixed resistor drain on an I-V graph
Straight line through the origin
What does the constant gradient of an ohmic graph show
Constant resistance
What does a steeper gradient mean on an ohmic I-V graph
Lower resistance as there’s more current flowing per volt
What is the ohms law equation
V = I R
How would you obtain negative values of I and V
Reverse the cell
Describe the resistance for a filament lamp
Resistance is not constant, so non ohmic
When does resistance increase
When current and pd increase
Why does resistance increase if I and V increase
Resistance increases as delocalised electrons collide with the metal’s ionic lattice, causing them to vibrate more, so its harder for the electrons to flow
What does an increase in resistance mean for temperature
Temperature increases
Explain what an increase in resistance means for current
Current decreases as its harder for electrons to flow
