resistance and factor affecting the resistance of a conductor

 

Resistance :--

Resistance is the property of a conductor to resist the flow of charges through it.

Also resistance is to oppose the flow of electric current in circuit. Resistance is represented by caps letter (R) . SI unit of R is    (Ω)

(Ω) :-- Its represented by Greek letter. And also called as omega

 

 

 

 

Factors on which the resistance of a conductor depends:--

 

(1) On its length

(2) On its area of cross – section

(3) On its nature of the materials

(4) And its Temperature

 

(1) Length :--

                  On applying the ohms law , we observed that resistance of the conductor depends on the length of the conductor.

Resistance of a uniform metallic conductor is directly proportional to its length which is denoted as (l). so that resistance will increased , when the length of the wire increases.

 

R    ∝       l

 

(2) Area of the cross-section  :--

                                           On applying the ohms law , we found that the resistance of the conductor  depends upon the area of the cross- section. The cross – section of the conductor also affects the resistance. The thick wire or conductor has large cross – section area for the electrons to be moved easily. Hence , the thick wire or conductor has less resistance than the thin wire or conductor of the same material and of the same length is used in the circuit.

 

Resistance of the conductor is inversely proportional to the area of the cross – section (A)

 

R     ∝   1/A

 

 

 

(3) Nature of the materials:--

                                       On applying the ohms law , we found that resistance of the conductors depends upon the nature of the materials. When we use the different materials of the same length and same cross – section , the reading of the ammeter is found different , or current is also different.

 

 

(4) Temperature :--

                        If the temperature of the conductor is increased , then the resistance of the conductor also get increased . similarly if the temperature of the conductor is decreased , its resistance also get decreased. It means , as temperature is changed , then the resistance of the conductor is also changed.