Question

The resistance of a wire of 0.01cm radius is 10ohms .if the resistivity of the material is 50 *10 to the power of -8 .find the length of the wire .(the and given before is wrong .how can the radius be 10 to the power -4:-( )

Answer 1

Thus so
_________
___________________________________@g ___________________________________

GIVEN

RESISTANCE = 10 OHM

. RADIUS = 0.01 CM = 1 / 100 CM

THEN

➿ R = p L / A

. 10 = 5 / 10 ^ 7 * L / 22 / 7 * 1 / 10 ^ 4

. L = 10 ^ 5 * 11 / 175

L = 10 ^ 6 / 159 CM

.

Answer 2

resistance of wire , R = 10 ohm

radius of base of wire , r = 0.01cm = 0.01/100 m

r = 1 × 10^-4 m

base area , A = πr² = 3.14 × (10^-4)² = 3.14 × 10^-8 m²

resistivity of the material of wire , ρ = 50 × 10^-8 ohm.meter

we know, formula

R = ρL/A

L = RA/ρ

= 10 ohm × 3.14× 10^-8m²/50 × 10^-8 ohm.meter

= 31.4/50 m

= 0.628 m

hence, length of wire is 0.628 m