Question

Enplain law of Resistance​

Answer 1

Answer:

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Explanation:

The following are the main laws of resistance:

(i) Resistance of a conductor is directly proportional to its length, provided temperature and other physical conditions remain unchanged.

It means that R ∝ l  i.e., if the length increases, the resistance also increases and if length decreases, its resistance also decreases.

(ii) Resistance of a conductor is inversely proportional to its area of cross section, other conditions remaining the same.

If A is the area of cross section, then :

R α 1/A

Or R α 1/πr2   where r is radius of the wire

Keeping the length same, if the radius of the wire is doubled then :

R α 1(2r)2  α 1/4r2

Or R α ¼.1/πr2,  or R becomes one fourth.

Similarly if r is made half, then :

R α 1/(r/2)2

α 4/r2 α 4(1/r2), or R becomes 4 times

This shows that R is α 1/A

(iii) R depends on the nature of the material of the conductor. It means, if we take equal lengths of wires of copper, aluminium and iron and all of the same cross-sectional area, their resistance are different from each other since they are of different materials.

Answer 2

Explanation:

The following are the main laws of resistance: (i) Resistance of a conductor is directly proportional to its length, provided temperature and other physical conditions remain unchanged. It means that R ∝ l i.e., if the length increases, the resistance also increases and if length decreases, its resistance also decreases. (ii) Resistance of a conductor is inversely proportional to its area of cross section, other conditions remaining the same. (iii) R depends on the nature of the material of the conductor. It means, if we take equal lengths of wires of copper, aluminium and iron and all of the same cross-sectional area, their resistance are different from each other since they are of different materials.Read more on Sarthaks.com - https://www.sarthaks.com/272665/state-and-explain-the-laws-of-resistance