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NCERT 12th Class Physics Ohm’s Law and Resistance

NCERT 12th Class Physics Ohm’s Law and Resistance


Ohm’s Law

Ohm’s law:  It states that “the current flowing through a conductor is directly proportional to potential difference between the ends of the conductor provided physical conditions like temperature, pressure etc.  remain the same”.
i.e.   VαI
or V = IR
Here V is apotential difference,I is current and R is Resistance of the conductor.
Resistance: It is the ability of a conductor to oppose the flow of electric current.
SI unit of resistance is ohm.
Factors on which resistance of a conductor depends:
  • Nature of the material of the conductor
  • Length of the conductor ‘l’
  • Area of cross-section ‘A’
  • Temperature
ie R ∝l
R ∝ 1/A
R= 𝜌l/A
Where 𝜌 is resistivity of the material of the conductor.
What to study the same topic in Hindi? click on Physics in Hindi
The resistivity of thematerial of a conductor:
𝜌=RA/l
If we have A=1m2 and l=1m
So 𝜌=R
The resistivity of the material of a conductor is defined as the resistance of the conductor having unit length and unit area of cross section. S.I. unit is ohm-meter  (Ω – m).
For the practice of Current Electricity problems & more, Click on NCERT Physics Class 12.
Ohmic conductors: Ohmic conductors are the conductors which obey ohms law and for which V-I graph is linear.Eg: Metallic conductor.
Click on Physics notes Class 12 for notes on various chapters and NCERT Solutions.
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