Question for Swapnil - 1

Electricity and Magnetism Level 3

Current flows through a cylindrical copper wire of resistance $10$ ohm and length $75\text{cm}$ . If the diameter of the wire is $14\text{cm}$ , find its specific resistance (in ohm-cm). (upto 2 decimal places). Take $\pi = \dfrac{22}{7}$

The answer is 20.53.

2 solutions

Ashish Menon
Apr 11, 2016

$\begin{aligned} \text{Using the formula}:-\\ R & = \dfrac{\rho × l}{a}\\ \\ \implies 10 & = \dfrac{\rho × 75}{\pi × r^2}\\ \\ \implies 10 & = \dfrac{\rho × 75}{\dfrac{22}{7} × 49}\\ \\ \implies \rho & = \dfrac{10 × 22 × 49}{75 × 7}\\ \implies \rho & = \boxed{20.53} \end{aligned}$

same way like you

Arun Garg - 5 years, 2 months ago

Great :+1:

Ashish Menon - 5 years, 2 months ago

Ashish nice Question, loved solving it.

Click here

Abhay Tiwari - 5 years, 1 month ago

Nice question but easy as it's direct substitution. You could have made it tough by asking to find the specific resistance in ohm-metre.

Abhiram Rao - 5 years, 1 month ago

Haha, alright, next time ;)

Ashish Menon - 5 years, 1 month ago

Sure. By the way what about that Mole Concept wiki?

Abhiram Rao - 5 years, 1 month ago

@Abhiram Rao – Nah, I saw that you haveosted feedback so I asked ;) you had deleted it I suppose XD

Ashish Menon - 5 years, 1 month ago

@Ashish Menon – I did it by mistake. But what I wrote in it was it requires many more topics.

Abhiram Rao - 5 years, 1 month ago

@Abhiram Rao – LOL, ok. :)

Ashish Menon - 5 years, 1 month ago

Abhiram Rao
Apr 21, 2016

Simple one. Just use R= pl/A and remember that the area(A) = pi*r^2 ...substitute the values and solve then

Question for Swapnil - 1

The answer is 20.53.

2 solutions

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