What is Resistor & Its Formula?

In this tutorial we are going to learn about What is Resistor & Its Formula?

RESISTOR: Resistance is property of resistor; It opposes the current by doing so it converts electric energy to heat energy

                        R =ρl/a             l – Length

                                                 a – Area

ρ – Resistivity of material in ΩM

Conductor –        Low Resistivity

Semiconductor – Medium Resistivity

Inductor –             High Resistivity

Super Conductor = ρ = 0

Eg.  Mercury at 4.15K temp

Rt = R0 (1+ αt )

R0 = Resistance of material at 0°C

 α  = Temp. Coefficient

t = Change in temp.


  • OHM’S LAW states that at constant temp. Current density is directly proportional to field intensity.
  • At constant temp, potential difference across Element is directly proportional to current flowing through elements 
  •  OHM’S LAW valid only when Conductivity and temp is constant .

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