Electricity Flashcards
What is Resistance measured in?
It is measured in Ohms. (symbol: Ω)
Define Resistance simply -
It is a measure of the difficulty of making current pass through the component.
How would you find Resistance using Voltage and Current?
Resistance = Voltage/Current (R = V/I)
What does one Ohm (symbol: Ω) represent?
It represents one Volt (symbol: V) per Ampere. (symbol: A)
Define Ohm’s Law -
The PD across a metallic conductor is proportional to the current through it, provided the physical conditions do not change.
Describe the voltage/current graph of a Resistor -
The graph is a straight line through the origin, the PD across the Resistor is proportional to the Current. The gradient is the resistance of the resistor.
What is the equation for Resistivity?
Resistivity, p = RA/L, where R = Resistance, L = Length and A = Cross-Sectional Area.
What is the unit for Resistivity?
The unit of resistivity is the Ohm Meter (symbol: Ωm)
How would you determine the Resistivity of a wire?
Measure the diameter of wire (d) using a micrometer at several different points and calculate the Cross-Sectional Area. (A)
Measure the Resistance (R) of different lengths (L) of the wire and plot a graph of R against L.
The Resistivity = graph gradient x A.
Define Superconductivity -
The property of zero electrical resistance in some substances at very low absolute temperatures.
When does a superconductor lose its superconductivity?
When its temperature is raised above its critical temperature.
What are superconductors used for?
They are used to make high-power electromagnets that generate very strong magnetic currents.
They are used in MRI Scanners and Particle Accelerators.
If components are in series, is the current entering a component the same or different to the current leaving the component?
It is the same.
