what is the diameter of the wire 1.4*10^16 electrons flow through a cross section of silver wire in 290 with a drift speed of 7*10^-4

Respuesta :

Answer:

The diameter is [tex]d = 0.00123 \ m[/tex]

Explanation:

From the question we are told that

   The number of electrons is  [tex]N = 1.40 *10^{16} \ electrons[/tex]

    The time taken is  [tex]t = 290 \mu s = 290 *10^{-6} \ s[/tex]

     The drift speed is  [tex]v = 7.*10^{-4} \ m/s[/tex]

Generally the number of electrons  that flows through the cross-sectional  area at the given time t is mathematically represented as

      [tex]N= n * A * v_d * t[/tex]

Here n is the number of conduction  electrons present in and the value is  

    [tex]n = 5.8*10^{28} / m^3[/tex]

A  is the cross-sectional area of the wire

So  

     [tex]1.4*10^{16} = 5.80 *10^{28} * A * 7*10^{-4} * 290 *10^{-6}[/tex]

=>  [tex]A = 1.189 *10^{-6} \ m^2[/tex]

Gnerally the area is mathematically represented as

     [tex]A = \pi* \frac{d^2}{4}[/tex]

=>   [tex]1.189 *10^{-6} = \pi* \frac{d^2}{4}[/tex]

=>   [tex]1.189 *10^{-6} = \pi* \frac{d^2}{4}[/tex]

=>  [tex]d = \sqrt{1.51369 *10^{-6}}[/tex]

=>  [tex]d = 0.00123 \ m[/tex]

The diameter of the silver wire in which the given number of electrons flows through is 1.22 × 10⁻³m

Given the data in the question;

  • Number of electron; [tex]N_e = 1.4*10^{16}[/tex]
  • Time taken to flow through the cross section of the silver wire; [tex]t = 290 us = 290 * 10^{-6}s[/tex]
  • Drift speed; [tex]v = 7*10^{-4}m/s[/tex]

From the expression of drift velocity, the number of electrons passing in through an area can be expressed:

[tex]N_e = n Avt[/tex]

Where [tex]N_e[/tex] is the Number of electron, n is the conduction electron density in silver( [tex]5.8*10^{28} electrons/m^3[/tex] ), A is the cross-sectional area, v is drift velocity or speed and t is the time.

We know that, Area; [tex]A = \pi r^2[/tex]

So

[tex]N_e = n (\pi r^2) vt[/tex]

We make "r", the subject of the formula

[tex]N_e = n (\pi r^2) vt\\\\r = \sqrt{\frac{N_e}{\pi nvt} }[/tex]

We substitute our values into the equation

[tex]r = \sqrt{\frac{1.4*10^{16}}{\pi *(5.8*10^{28}m^{-3})*(7.10*10^{-4}m/s)*(290*10^{-6}s)} } \\\\r = \sqrt{3.73*10^{-7}m^2}\\\\r = 6.1* 10^{-4}m[/tex]

We know that, Diameter;[tex]d = 2*r[/tex]

So,

[tex]d = 2 * (6.1*10^{-4}m)\\\\d = 1.22 * 10^{-3}m[/tex]

Therefore, the diameter of the silver wire in which the given number of electrons flows through is 1.22 × 10⁻³m.

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