Question

A wire of resistance 4 ohm is used to wind a coil of radius 7 cm a wire has a diameter of 1.4 mm and specific resistance of its material 22 10 raise to power 7 ohm metre find the number of terms in the coil

Answer 1

Answer:

Explanation:

Given A wire of resistance 4 ohm is used to wind a coil of radius 7 cm a wire has a diameter of 1.4 mm and specific resistance of its material 22 10 raise to power 7 ohm metre find the number of terms in the coil .

Given resistance of wire, R = 4 ohms

Radius of coil r = 7 cm = 0.07 m

Diameter d = 1.4 mm = 1.4 x 10^-3 m

Specific resistance = 2 x 10^-7 ohm mtr.

We know that area of wire = π r^2

 r = d/2 = 1.4 x 10^-3 /2

So A = 22/7 x (1.4 x 10^-3 / 2)^2  

   A = 1.54 x 10^-6 sq m

Now let length of wire be l

So resistance = ρ L / A

  L = A R / ρ

  L = 4 x 1.54 x 10^-6 / 2 x 10^-7

  L = 30.8 m

So perimeter of each turn of coil = 2 π r

                                              = 2 x 22/7 x 0.07

                                           = 0.44 m

Now number of turns in the coil will be l / perimeter = 30.8 / 0.44

                                                                            = 3080 / 44 = 70

Number of turns in the coil will be 70

Answer 2

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