CAPE Physics Unit 2 · 2019 · Paper 1 · Question Q10

What is the magnetic flux density at the centre of a long solenoid, given that the number of turns per unit length is 12\text{ turns per centimetre} and the current passing is 3\text{ A}? (Assume \mu_0 = 4\pi \times 10^{-7}\text{ H m}^{-1}.)

1. (A)144\pi \times 10^{-5}\text{ T}
2. (B)1.44\pi \times 10^{-5}\text{ T}
3. (C)144\pi\ \mu\text{T}
4. (D)144\pi\text{ T}