You are designing a solenoid to produce a 2.0-kG magnetic field. You wish to wrap your insulated wire uniformly around a cardboard tube that is 8.0 cm in diameter and 58 cm in length, and you have a power supply that will allow you to pass a current of 2.5 A through the solenoid. Determine the total length of wire you will need in order to build the solenoid you have designed.

92.7 km

Explanation:

Since the magnetic field due to a solenoid is given by B = μ₀Ni/L where  μ₀ = permeability of free space = 4π × 10⁻⁷ H/m, N = number of turns of solenoid, L = length of cardboard tube = 58 cm = 0.58 m, , i = current in wire = 2.5 A and l = length of wire.

So, N = BL/μ₀i

Since B = 2.0 kG = 2.0 × 10³ G = 2.0 × 10³ × 10⁻⁴ T = 2.0 × 10⁻¹ T = 0.2 T

So, substituting the variables into the equation, we have

N = BL/μ₀i

N = 0.2 T × 0.58 m/(4π × 10⁻⁷ H/m × 2.5 A)

N = 1.16 Tm/(31.416 × 10⁻⁷ HA/m)

N = 0.0369 × 10⁷ turns

N = 0.0369 × 10⁷ turns

N = 3.69 × 10⁵ turns

length of wire l = NC where N = number of turns and C = circumference of tube = πD where D = diameter of tube = 8.0 cm = 0.08 m

So, l = NC

= NπD

= πND

= π × 3.69 × 10⁵ turns × 0.08 m

= 0.9274 × 10⁵ m = 9.274 × 10⁴ m

= 92.74 × 10³ m

= 92.74 km

≅ 92.7 km

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