Question

18. According to Ohm's law, resistance of
the conductor depends on length, area of
cross section and nature of the material.
Derive an expression to prove the relation
between the above factors.​

Answer 1

Answer:

Ohm's law states that:

• Resistance is directly proportional to length of the conductor.
• Resistance is indirectly proportional to the area of cross section.
• Resistance changes changes according to the nature of the material.
• Resistance also changes according to the temperature of the conductor.

The important factors here for the change in the resistance is the length of the conductor and the area of cross section.

So, we can say that:

• R ∝ length
• R ∝ 1/Area of cross section

Hence, R ∝ l/A

Now, using a variable to eliminate the sign of proportionality.

• R = ρ l/A

So, At last we got the expression to prove the relation between the factors.

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Answer 2

Answer:

we know that resistance is directly proportional to length of wire (R@L),

-resistance is inversely proportional to area cross section of wire.

Hence, R@L/A

R=pL/A

where p=resistivity (or)specific resistance