An electron that travels through wires of the external circuit witnesses resistance. Resistance is termed as the hindrance to the flow of electric charge. The electron does not travel from one terminal to another in a linear direct route. Instead, it follows a zig-zag path resulting from countless collisions with fixed atoms inside the conducting material.
Electrons witness some kind of hindrance to their movement known as resistance. The potential difference between the two terminals help is the movement of charge but the resistance tries to come in the way of it. The rate at which the charge flows across a circuit from one terminal to another is caused due to the combined effect of both- resistance and potential difference.
The electrical resistance of a conductor (electrical) is a measure of the difficulty to pass the electric current through a conductor. Electrical conductance is the ease with which an electric current passes. Electrical resistance has some parallels to the notion of mechanical friction.
The SI unit of electrical resistance is called ohm. Electrical conductance is measured in the unit of Siemens. A uniform cross section object has a resistance proportional to its resistivity and also its length while it is inversely proportional to the cross-sectional area. Except superconductors, all materials show some kind of resistance.
MEASUREMENT AND MORE
The resistance of an object is also defined as the ration of voltage that runs through it to the current that passes through it.
Where ‘r’ is resistance, ‘v’ is voltage and ‘I’ is the current.
With more resistance in a given circuit, there would be less flow of electricity through it. The resistance of a wire increases with increase in length and decreases with decrease in length.
Resistance was discovered by Georg Simon Ohm in 1827. Ohm’s law states that with temperature as constant, the voltage between any two points in a conductor changes directly with change in the current between the two points.
VARIABLES AFFECTING ELECTRICAL RESISTANCE
- The length is directly proportional to the resistance. More collisions (between atoms and charge carriers) occur in a longer wire and more collisions mean more resistance.
- Cross sectional area is inversely proportional to resistance. More area results in less resistance.
- Material that the substance is made of affects resistance. Some materials are good resistors while others are not. Resistivity of a material depends on material’s temperature and its electronic structure.
USES OF ELECTRICAL RESISTANCE
- It is useful in explaining the relationship between the voltage (the amount of electrical pressure) and the flow of electricity (current).
- Resistors come in handy in electrical circuits to supply electrical resistance.