A coil is formed by winding 190 turns of insulated 16 gauge copper wire (diameter = 1.9 mm) in a single layer on a cylindrical form of radius 9.2 cm. What is the resistance of the coil? Neglect the thickness of the insulation. (Take the resistivity of copper to be 1.69 × 10-8 ohm-m.)

Respuesta :

Explanation:

The given data is as follows.

number of turns = n = 190 turns

radius = r = 9.2 cm = 0.092 m

diameter of copper wire = d = 1.9 mm

radius of copper wire = [tex]r_{c}[/tex] = [tex]\frac{d}{2}[/tex]

                     = [tex]\frac{1.9}{2}[/tex]    

                     = [tex]0.95 \times 10^{-3}[/tex] m

where,  A = cross sectional area of the wire

As, length of each turn of wire is 2pr where r is radius of the coil.

  L = 190(2pr)

     = [tex]190 \times 6.28 \times 0.092 m[/tex]

      = 109.77 m

The cross sectional area of the wire is as follows.

       A = [tex]\pi r^{2}_{c}[/tex]

           = [tex]3.14 (0.95 \times 10^{-3} m)^{2}[/tex]

          = [tex]2.83 \times 10^{-6} m^{2}[/tex]

It is given that resistivity of copper wire is [tex]1.69 \times 10^{-8} \ohm[/tex]

              R = [tex]\rho \frac{L}{A}[/tex]

                  = [tex]1.69 \times 10^{-8} \ohm \times \frac{109.77}{2.83 \times 10^{-6} m^{2}}[/tex]

                 = [tex]65.53 \times 10^{-2} \ohm[/tex]

Thus, we can conclude that resistance of the coil is [tex]65.53 \times 10^{-2} \ohm[/tex].

Answer:

The resistance of the coil is 0.655 Ω

Explanation:

Given that,

Number of turns = 190 turns

Diameter of coil= 1.9 mm = 0.95 mm

Radius of single layer = 9.2 cm

Pressure = 16 gauge

We need to calculate the length of the wire

Using formula of length

[tex]L=n2\pi r[/tex]

Where, n = number of turns

r = radius of cylinder

Put the value into the formula

[tex]L=190\times2\pi\times9.2\times10^{-2}[/tex]

[tex]L=109.8\ m[/tex]

We need to calculate the area of cross section

Using formula of area

[tex]A=\pi\times r^2[/tex]

Put the value into the formula

[tex]A=\pi\times(0.95\times10^{-3})^2[/tex]

[tex]A=0.000002835\ m^2[/tex]

[tex]A=2.83\times10^{-6}\ m^2[/tex]

We need to calculate the resistance of the coil

Using formula of resistivity

[tex]R=\dfrac{\rho\times l}{A}[/tex]

Put the value into the formula

[tex]R=\dfrac{1.69\times10^{-8}\times109.8}{2.83\times10^{-6}}[/tex]

[tex]R=0.655\ \Omega[/tex]

Hence, The resistance of the coil is 0.655 Ω