Current, Resistance and Potential Difference Flashcards
Where does the current flow?
From the positive side of a cell to the negative side of the cell
Which side of the cell is positive?
The long side of the cell
Which side of the cell is negative?
The short side.
Define potential difference (2)
The push in the circuit.
The work done per unit charge.
Describe how the potential difference affects the current.
The greater the potential difference, the greater the current.
What is used to measure the current through a component?
An ammeter
What is used to measure the potential difference across a component?
A voltmeter.
Where is an ammeter placed in a circuit?
It is placed in series with the component it’s measuring the current of.
Where is a voltmeter placed in a circuit?
It is placed in parallel with the component it’s measuring the potential difference of.
Describe how the resistance of a component affects the current in a circuit if the potential difference is the same.
As the resistance increases, the current decreases.
What in a circuit has resistance?
A component in a circuit has resistance.
Describe what causes current. (3)
• The current is electrons that are moving around the circuit.
• These move in the opposite direction as they are attracted to the positive side of the cell.
• The electrons experience an electrical force from the cell, which causes movement.
Define current.
The rate of flow of the charge.
State the equation involving charge, current and time.
charge = current × time
Q = I × t
Describe the current in a series circuit.
The current at any point in the circuit is the same.
Describe the potential difference across a cell in a series circuit.
The potential difference across the cell is equal to the potential difference across each component in series.
Describe the current in a parallel circuit.
The circuit splits at a point where the circuit has two paths to follow.
Describe the potential difference across a cell in a parallel circuit.
The potential difference across the cell is equal to the potential difference across each branch.
State the equation that links energy transferred, charge and potential difference.
energy transferred = charge × p.d.
E = Q × V
State the equation that links potential difference, current and resistance.
potential difference = current × resistance
V = I × R
How can we calculate the resistance? (2)
• By measuring the potential difference across a component.
• By measuring the current through a component.
