Physics notes for class 12 Electrical Resistance
In this article, ‘Electrostatic Resistance’ from Class 12th Physics is being discussed.
Electrical Resistance
Resistance: The hindrance offered by a conductor to the flow of current.SI unit of resistance is ohm.The Electrical Resistance of a conductor depends on its length‘l’,cross-sectional area ‘A’ and nature of material and is given by
R= 𝜌l/A
where 𝜌 is the resistivity of the material of the conductor.
Colour code for carbon resistances: Very high resistances are made of carbon. The value of high resistance is specified by four bands of different colors.
The first three bands represent the value of resistance while the last band represents tolerance. The first band represents the first digit, the second band represents the second digit and thethird band represents multiplier in powers of 10. The color of the fourth band tells the tolerance.The absence of thefourth band means a tolerance of 20%.
Ques: Determine the resistance of a resistor with the following colors for the rings:
yellow, red, orange,gold.
Ans: We know numbers for yellow, red, orange, goldis 4,2,3 and 5% respectively.
R = 42×103Ω ±5%
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