Topic 10 🔋🎡 Flashcards
If there is a potential difference in the circuit, there will also be a…
Current
How is current defined?
As the rate of flow of charge (or electrons) around a circuit
What are the units of charge?
Coulombs, C
What are the two ways that a component can be connected in a circuit?
- series (same loop)
- Parallel (adjacent loop)
Voltage is also know as…
Potential difference
How does potential different across two components vary when connected in series?
In a series circuit the total PD is shared between each component.
How does the potential difference across two components vary when connected in parallel?
In a parallel circuit the PD across each component is the same.
If two resistors are connected in parallel, what can be said about their combined total resistance?
Their total resistance is less than the smallest of the two individual resistances.
If two resistors are connected in series what can be said about their total resistance?
Their total combined resistance is equal to the sum of the two individual resistances.
When must a voltmeter be placed in a circuit?
In parallel with the component that is being measured.
Give an equation relating to PD with energy transferred and charge.
Potential difference (V) = energy transferred (J) / charge (C)
V=E/Q
A volt can be described as a…
Joule per coulomb
What is an electric current?
The rate of flow of charge.
State the equation linking charge, current and time. Give the units for the quantities involved.
Q = I x t
Charge (Coulombs), Current (Amps), Time (Seconds)
What can said about the value of current at any point in a single closed loop?
Current is the same at all points in a closed loop.
What two facets does the current in a circuit depend on?
- PD (V)
- Resistance (Ohms)
What equation should be used to calculate potential difference of current resistance known? State the units for all three quantities.
V = I x R
Potential Difference (V), Current (A), Resistance (Ohms)
What is an ammeter and where must it be connected in a circuit?
An ammeter measures current. It is placed in series with the component it is required to measure.
What happens when current reaches a junction in the circuit?
Current is conserved; total current remains the same, and it’s split between the two branches
How does resistance affect current in a circuit?
As the total resistance of a circuit increases, the current flowing through the circuit decreases.
How can the current circuit be varied?
Using a variable resistor.
Give the equation linking current with resistance
p.d (V) = current (A) x resistance (Ohms)
V = I x R
How is total resistance affected by two resistors in series?
Total resistance increases; it is equal to the sum of the two resistors.
How is the total resistance affected by two resistors in parallel?
The total resistance decreases; it is less than the resistance of the resistor with the lowest resistance
What is an Ohmic Conductor? State the conditions required.
- A conductor for which current current and potential difference directly proportional.
- Resistance remains constant as current changes.
- Temperature must be constant.
List four components for which resistance is not constant as current changes.
- Filament Lamps
- Diodes
- Thermistors
- Light Dependant Resistors (LDR’s)
