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Temperature Dependence of Resistivity Temperature Dependence of Resistivity :- The resistivity of almost all materials depends on temperature, but not all materials show the same temperature dependence. In a limited temperature range (about 100 ºC or less), the resistivity of a conductor is expressed by the following relation :- …..(1) Here ρt…
Carbon Resistor (Carbon Resistor Colour Code) Resistors used in laboratories and for domestic use are of two major types :- Wire bound resistors and Carbon resistors. 1. Wire bound resistors :- The selection of materials of wire bound resistors is done in such a way that their resistivity is relatively insensitive to temperature i.e., there…
Define Resistivity | Resistivity | Unit of Resistivity Resistivity | Define Resistivity :- In the previous article “Resistance” we saw that the resistance of a conductor is given by the following formula : …..(1) Here we say that ρ is a proportionality constant. In physics, to define a proportionality constant we use…
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Resistance | SI Unit of Resistance Resistance | SI Unit of Resistance :- G.S. Ohm in 1828, discovered a basic law regarding the flow of current(I) in a conductor and potential difference(V) across its terminals, called Ohm’s Law. According to Ohm’s Law :- Or where the constant of proportionality R is called the resistance…
Ohm’s Law | What is Ohm’s Law Ohm’s Law | What is Ohm’s Law :- In 1826, the German scientist Dr. George Simon Ohm expressed the relationship between the potential difference across a conductor and the current flowing in it by a law, which is called Ohm’s law. According to Ohm’s law, “If the…
Microscopic form of Ohm’s Law (Relation between Current density, Conductivity and Electric field) Microscopic form of Ohm’s Law :- This form of Ohm’s law is a relation between current density J, conductivity σ and the electric field E on microscopic level. In the previous article “Relation Between Current and Drift Velocity” we proved that…
Relation Between Current and Drift Velocity Relation Between Current and Drift Velocity :- Let a battery of e.m.f. V is applied across a conductor of length L. An electric field E (= V/L) is set up inside the conductor and the electrons drift towards the positive terminal of the battery with drift velocity vd….
Drift Velocity Drift Velocity :- In the absence of applied potential difference, electrons have random motion and have only thermal velocity. When a battery is connected across the terminals of the conductor, then in addition to thermal velocity, they acquire an acceleration due to applied electric field. Now the electrons acquires a velocity component…
Electric Current Moving electric charges generate electric current. Any medium in which electric charge is free to move is called a conductor of electricity. Electric charges flow from a higher potential energy state (higher electric potential) to a lower potential energy state (lower electric potential). Positive charges flow from high potential to low potential and…
Current Density The concept of current density is introduced to specify the current with direction at microscopic level at a point. “Current density is defined as a vector whose magnitude is equal to the magnitude of the current flowing per unit area normal to that point.“ Always remember that area is normal to the direction…