Electicity Flashcards
What is the definition of current? (Include the equation)
The rate of flow of charge, current= charge/time
What are the two different kinds of current flow?
Electron flow: from negative to positive and is the direction that electrons actually flow in a circuit.
Conventional current flow: from positive to negative and is more comely used to describe motion.
What is the definition of potential difference? (Include the equation)
Work done per coulomb of charge, potential difference= work done/charge
What is the definition of resistance?
The measure of how difficult it is for current to flow in a circuit.
What is an ohmic conductor?
This is represented by a straight line going through the origin, meaning that current flow is directly proportional to the potential difference (providing the temp is constant)
What is resistivity?
Resistance multiplied by the cross sectional area over length.
What is a superconductor?
This is a material that has zero resistance and is below a critical temperature.
What is an example of a superconductor?
MRI’s and high speed trains, as they have stronger magnetic fields
What is a semiconductor? And give two examples.
Semiconductors is when the resistance changed based off external conditions.
LDR (light dependant resistor): when light intensity increases their resistance decreases.
Thermistors: when the temperature increases the resistance decreases.
What is power? (Include equations)
The rate of energy transfer, P=W/t, P=VI
Describe how voltage and current is shared in a series circuit.
Current is the same in all positions in a series circuit, Potential difference is split between all the components.
Describe how voltage and current is in a parallel circuit.
Current is split between each component, potential difference over each loop is the same.
What is kirchoffs first law?
current going in = current going out
what is kirchoffs second law?
emf= total pd (in series)
