Question

2. A wire 4.00 m long and 6.00 mm in diameter has a resistance of 15.0 mΩ. A potential difference of 23.0 V is applied between the end. a) What is the current in the wire? b) Calculate the resistivity of the wire material. c) Try to identify the material.

Answer 1

Answer:

Explanation:

a )

current in the wire = potential diff / resistance

= 23 / (15 x 10⁻³ )

= 1.533 x 10³ A .

b )

For resistance of a wire , the formula is

R = ρ L / S where ρ is specific resistance , L is length and S is cross sectional area of wire

putting the given values

15 x 10⁻³ = 4ρ / π x .003²

ρ = 106  x 10⁻⁹ ohm. m

= 10.6 x 10⁻⁸ ohm m

The metal wire appears to be platinum .

Answer 2

(a) The current in the wire is 1.533 x 10³ A

(b) The resistivity of the wire material is 10.6 x 10⁻⁸ Ωm

(c) The material of the wire is Platinum

Ohm's Law and resistivity:

(a) According to the Ohm's Law:

V = IR

where V is the potential difference

I is the current

and R is the resistance

So,

I = V/R

I = 23 / (15 x 10⁻³ )

I = 1.533 x 10³ A

(b) The resistance of a wire is expressed as:

R = ρ L / A

where ρ is the resistivity,

L is length

and A is the cross-sectional area

15 x 10⁻³ = 4ρ / π x .003²

ρ = 106  x 10⁻⁹ Ωm

ρ = 10.6 x 10⁻⁸ Ωm

The metal from which the wire is made is platinum.

Learn more about Ohm's Law:

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