AQA Combine Physics 6.2 Flashcards
Revision for Paper 1
Describe an I-V graph for a diode
Current will only flow in one direction (there is a very high resistance in the other direction)
Describe an I-V graph for an ohmic resistor (e.g. resistor at a constant temperature)
Current (at constant temperature) is directly proportional to potential difference
What happebs to the resistance of an ohmic conductor (such as a wire) when the current changes?
The resistance of ohmic conductors doesn’t change with current
For a given potential difference, what happens to the current when the resistance increases?
The current gets smaller
In a single closed loop, what value would the current have at any point?
The same value
What is electrical current and what determines the size of the current?
The flow of electrical charge, determined by the rate of flow
What are the two ways of joining an electrical component?
In series or in parallell=
Where are LDRs commonly found?
LDRs are used as automatic night lights/burglar detectors
Where are thermistors commonly found?
Car engine temperature sensors/electronic thermostats
Describe direct current supplies
Current that is always flowing in the same direction (created by a direct voltage)
What type of electricity supply is mains?
Alternating current (AC)
How can the total current through a parallel circuit be calculated?
It is the sum of the currents through the separate components
What is the equation for Rtotal?
Rtotal = R1 + R2
What equation links power, current and potential difference?
Power = current x potential difference P = I V
What equation links power, current and resistance?
Power = current 2 x resistance P = I2 R
What is the function of the Earth wire (green/yellow)?
Acts as a safety device, stopping the appliance casing from becoming live (OV)
What is the function of the live wire (brown)?
Provides the alternating potential difference (230V)
Describe the characteristics of the UK mains supply
230V AC with a frequency of 50Hz
How are step-up transformers used within the National Grid?
Step-up transformers increase the potential difference of the National Grid to 400,00V