PHYSICS DEFINITION:
Ohm’s Law: A Conductor obeys Ohm’s law if its current is
directly proportional to the potential difference across its ends.
Ohmic: Component that obeys Ohm’s Law.
Non-ohmic: Component that does not obey Ohm’s Law.
PHYSICS KEYWORD LIST:
I-V Characteristic: Graph of current against voltage for a
particular component of an electrical circuit.
Resistor: Electrical component whose resistance in a circuit
remains constant, and is independent of current or potential difference.
NTC Thermistor: A device whose resistance decreases rapidly
when the temperature increases.
Threshold Voltage: Minimum forward potential difference across
a diode at which it starts to conduct.
Light-Dependent Resistor (LDR): A component whose resistance
decreases with light intensity.
Delocalised Electron: Electron that is not attached to a
specific ion, but is free to move throughout the crystal lattice.
Resistivity: Property of material; it measures its
electrical resistance, defined by p = (RA)/L. Unit: Ω m
PHYSICS CHAPTER WISE SUMMARY:
A conductor obeys Ohm’s Law if the current in it is directly
proportional to the potential difference across its ends.
Ohmic components include a wire at constant temperature and
a resistor.
Non-ohmic components include a filament lamp and a
light-emitting diode.
A semiconductor diode allows current in one direction only.
As the temperature of a metal increases, so does its
resistance.
A thermistor is a component that shows a rapid change in
resistance over a narrow temperature range. The resistance of an NTC thermistor
decreases as its temperature is increased.
The resistivity p of a material is defined as p = (RA)/L.
The unit of resistivity is the ohm metre. (Ω m)
PHYSICS IMPORTANT NOTES:
Resistance is inversely proportional to cross-sectional
area.
Resistance is directly proportional to the length of the
wire.
Resistance = (Resistivity x length)/Cross-sectional area
Resistivity = (Resistance x Cross-sectional area)/length.
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