Resistance Flashcards
What is EMF(electromotive force-from power supply)
Work done per unit charge- When one type of energy is converted into electrical
What is Pd(potential difference-across a component)
Energy per unit charge- When electrical energy is converted into other types of energy
Voltage and current graph for resistor
Voltage and current are directly proportional meaning resistance is constant
Voltage and current graph for a filament lamp
As voltage increases current increases at a decreasing rate, resistance increases
Ohms law
Current and voltage are directly proportional, provided external conditions remain constant
Define resistance
Voltage per unit current
Define resistivity
Product of resistance and cross sectional area per unit length
Electrical energy equation
Energy= current x voltage x time
Explain super conductivity
When metals are cooled enough so that their resistance becomes 0 due to low temperatures. (Critical Temperature)
What elements are used to achieve super conductivity
Liquid Nitrogen and Liquid Helium
Equation for electrons passing
Charge/energy
Transition temp meaning
Temp at which material loses all its resistivity
Uses for super conductors
Coil for MRI machine, power cables and magnets
