Current and Potential Difference Flashcards
Define ‘current’
The flow of electric charge around the circuit
When will current only flow across a component?
If there is a potential difference across that component
What is the unit for current?
Ampere: A
Define ‘potential difference’
The driving force that pushes the current around
What is the unit for potential difference?
Volts: V
Define ‘resistance’
Anything in the circuit which slows the flow (of the current) down
What is the unit for resistance?
Ohm: Ω
The greater the resistance across a component, the ____ the current that flows
(for a given ____ ____ across the component)
The greater the resistance across a component, the smaller the current that flows
(for a given potential difference across the component)
Which 2 factors does total charge through a curcuit depend on?
- Current
- Time
Current is the ____ of ____ of ____
Current is the rate of flow of charge
Write the formula triangle for current, total charge, and time
Current = charge / time
Current is measured in ____
Amperes (A)
Charge is measured in ____
Coulombs (C)
Time is measured in ____
Seconds (s)
More charge passes around the curcuit when a ____ current flows
More charge passes around the curcuit when a bigger current flows
Example:
A battery charger passes a current of 2.5 A through a cell over a period of 4 hours. How much charge does the charger transfer to the cell altogether?
Q = I x t = 2.5 x (4 x 60 x 60) = 36 000 C (36 kC)
Potential difference is the ____ ____ per ____ ____ ____
Potential difference is the work done per unit of charge
Give the formula for potential difference, work done, and coulombs
P.D. (V) = work done (W) / charge (Q)
Potential difference across an electrical component is…
… The amount of energy transferred by that electrical component (e.g. to light and heat energy by a bulb) per unit of charge
