Question

A cylindrical wire length l and radius r and resistance r the resistance of another wire of same material but of twice of length and half radius mcq questions answer is

Answer 1

Question :-

A cylindrical wire length l and radius r and resistance r the resistance of another wire of same material but of twice of length and half radius mcq questions answer is :

Answer :

Material is the same .

Hence the resistivity is same .

Length is twice and radius is half .

R₂ = p l₂ / a₂

    = p l₂ / ( π r₂² )

r₂ = 1/2 r

l₂ = 2 l

So :

R = p ( 2 l₁ ) / ( 1/2 r )²π

= > p ( 2 l ) / ( 1/4π r² )

= > p ( 2 l . 4 ) / π r²

= > p 8 l / π r²

Hence the resistance becomes eight times of the original .

Answer 2

here is your Answer ✍️✍️✍️


this can be simply done by the general formulas of resistance resistivity and all other related to it


for further you refer to the attachments

hope it helps you ❤️❤️