P2 Flashcards
Voltmeter
measures the potential difference across a component
Ammeter
measures current
Battery / Cell
Provides energy to the electrons in a circuit
Switch
Connects / Disconnects the circuit
Resistor
Resists current
Diode
Keeps current flowing in one direction
Thermistor
- Resistance decreases as temperature increases
- When temperature increases, additional energy can be used to increase the kinetic energy of electrons (current)
- More current = less resistance
Light Dependant Resistor
Resistance decreases as light increases
- When light increases, additional energy can be used to increase the kinetic energy of electrons (current)
- More current = less resistance
Voltage
Amount of energy supplied to each Colomb
Potential Difference
- The difference in energy per charge between 2 points in a circuit
- Shows how much energy is supplied to a component
- YOU ALWAYS CALCULATE THIS
Current Calculation?
Current = Charge / time
Energy Calculation?
Energy = Charge x Potential Difference
Current in a series circuit…
Always stays the same
Current in a parallel circuit…
Splits between the pathways
Potential Difference in a series circuit…
Is shared amongst the components
Voltage in a parallel circuit…
Stays the same
More resistors in series…
= more resistance
More resistors in parallel…
= more pathways = more current = less resistance
Ohms law
- Current flowing through a resistor is directly proportional to the potential difference
- Current across a resistor is inversely proportional to the resistance
What is the only condition for ohms law?
If Temperature is Constant
Resistance in Parallel circuit?
- Total resistance is always less than the lowest resistance in the circuit
- Rt = 1 + 1
R1 R2
What is the gradient on a V-I graph for a resistor?
Resistance
If a component obeys ohms law what WILL be constant?
Resistance
Does a filament Bulb follow Ohm’s law?
- Up to a certain point where the line starts to curve
- This is because after a while, temperature increases which leads to more resistance leading to less current