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Two insulated copper wires of similar overall diameter have very different interiors. One wire possesses a solid core of copper, with a circular cross section of radius 1.53 mm. The other wire is composed of 19 strands of thin copper wire bundled together. Each strand has a circular cross section of radius 0.306 mm. The current density ???? in each wire is the same. ????=1750 A/m2 Two circles. One circle is solid, whereas the other contains 19 tightly packed smaller circles How much current does each wire carry? solid wire current: A stranded wire current: A The resistivity of copper is ????=1.69×10−8 Ω·m. What is the resistance of a 3.25 m length of each wire? solid wire resistance: Ω stranded wire resistance: Ω

Respuesta :

Answer:

a

 Solid Wire     [tex]I  =   0.01237 \  A [/tex]      

  Stranded  Wire  [tex]I_2  =   0.00978 \  A [/tex]

b

  Solid Wire   [tex]R  = 0.0149 \ \Omega [/tex]

   Stranded  Wire  [tex]R_1  = 0.0189 \ \Omega [/tex]

Explanation:

Considering the first question

From the question we are told that

  The  radius of the first wire is  [tex]r_1  = 1.53 mm = 0.0015 \  m[/tex]

  The radius of  each strand is  [tex]r_0 =  0.306 \ mm =  0.000306 \ m[/tex]

  The current density in both wires is  [tex]J  =  1750 \  A/m^2[/tex]

Considering the first wire

     The  cross-sectional area of the first wire is

      [tex]A   = \pi  r^2[/tex]

= >  [tex]A   = 3.142 *  (0.0015)^2[/tex]

= >  [tex]A   = 7.0695 *10^{-6} \  m^2 [/tex]

Generally the current in the first wire is    

     [tex]I  =  J*A[/tex]

=>  [tex]I  =  1750*7.0695 *10^{-6}[/tex]

=>  [tex]I  =   0.01237 \  A [/tex]

Considering the second wire  wire

The  cross-sectional area of the second wire is

     [tex]A_1  =  19 *  \pi r^2[/tex]

=>     [tex]A_1  =  19 *3.142 *  (0.000306)^2[/tex]

=>  [tex]A_1  =  5.5899 *10^{-6} \  m^2[/tex]

Generally the current is  

      [tex]I_2  =  J  *  A_1[/tex]

=>    [tex]I_2  =   1750  *  5.5899 *10^{-6} [/tex]

=>    [tex]I_2  =   0.00978 \  A [/tex]

Considering question two  

 From the question we are told that

     Resistivity is  [tex]\rho  =  1.69* 10^{-8} \Omega \cdot m[/tex]

     The  length of each wire  is  [tex]l =  6.25 \  m[/tex]

Generally the resistance of the first wire is mathematically represented as

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

=> [tex]R  =  \frac{  1.69* 10^{-8} * 6.25 }{ 7.0695 *10^{-6} }[/tex]

=> [tex]R  = 0.0149 \ \Omega [/tex]

Generally the resistance of the first wire is mathematically represented as

    [tex]R_1  =  \frac{\rho *  l  }{A_1}[/tex]

=> [tex]R_1  =  \frac{  1.69* 10^{-8} * 6.25 }{5.5899 *10^{-6} }[/tex]

=> [tex]R_1  = 0.0189 \ \Omega [/tex]