what is the resistivity of a metallic wire if we double its area of cross section and the length remains same.please answer it as soon as possible?
Answers
Miguel Gonzales is absolutely correct, your stretched wire will have 4 times the resistance.
Here is the math for this as presented when previously asked where the starting wire had 50 ohms resistance.
Let us take a material that has a resistivity of 392.7 rho. This is the p that resistivity is measured in. This means that a 1 meter cube would measure 1 ohm from side to side. Further let us imagine a wire of this high resistance material being 10 mm in diameter and having a length of 10 mm. Like this:
Now we stretch this material to twice its length but the volume remains the same. Now our material looks like this:
No, the diameter does not halve, it is the volume that stays the same. You may do the math for that bit.
Using the formula for resistance, R, for this material’s resistivity on the original material for your 50 ohms as stated in your question:
Where
l=length
A=Cross Sectional Area.
Our stretched material, using the same formula, is: