Answer:
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
