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How Does the Resistance of a Wire Change When: Its Diameter is Tripled? - Science

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Question

How does the resistance of a wire change when:

 its diameter is tripled? 

 

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Solution

Resistance, 

`R=l/A`

where l = length of  wire
            A= area of cross-section of the wire 

When the diameter is tripled, d' = 3Radius, r' = 3r

Area of cross-section, `A=Api^2=A(3pi)^2=9Api^2=9A`

Thus, the area of cross-section will become nine times. 

Then the new resistance, 

`R'=l/A` 

`R'=l/9A` 

`R'=R/9` 

Thus, the resistance will be reduced by nine times.

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Chapter 1: Electricity - Exercise 4

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Lakhmir Singh Physics (Science) [English] Class 10
Chapter 1 Electricity
Exercise 4 | Q 22.2

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