Question

A cylinder of a material is 10 cm long and has a cross-section of 2 cm2 . If its resistance along the length be 20 ohm ,what will be its resistivity ?

Answer 1

Length=10cm
Cross section=2cm sq.
Resistance=20ohm
By the formula of resistivity we get,
20×2/10=4ohm.m

Answer 2

Solution :

We are given with :

Length of cylinder , L = 10 cm

And Area = 2 cm²

The given resistance = 20 ohm =20 Ω

We know very well that :

$R = p \ \frac{L}{A}$

From this formula we can find p = RA/L

p = 20×2/10 = 4 ohm - cm = 0.04 ohm - m

Here p = resistivity .

The required resistivity is 0.04 ohm - m