BPSC 70th Prelims Exam Held on 13 Dec 2024

Concept:Tesla (T) is the SI unit of magnetic flux density. It can be expressed using base SI units as $1\ \text{T} = 1\ \frac{\text{N}}{\text{A}\cdot\text{m}}$.Explanation:From Lorentz force: magnetic force $F = qvB$ or $F = I\ell B$. Rearranging gives $B = F / (I\ell)$. The SI unit of force is Newton (N), current is Ampere (A), and length is meter (m). Thus $1\ \text{T} = 1\ \frac{\text{N}}{\text{A}\cdot\text{m}}$.Check options:- Option A (Ampere/Newton) is inverse of correct unit.- Option B (Newton/Coulomb) is unit of electric field (volt/meter).- Option C (Newton/ampere-second) simplifies to $\frac{\text{N}}{\text{A}\cdot\text{s}} = \frac{\text{kg}\cdot\text{m/s}^2}{\text{A}\cdot\text{s}} = \frac{\text{kg}\cdot\text{m}}{\text{A}\cdot\text{s}^3}$, not tesla.- Option D (Newton per ampere meter) exactly matches $1\ \text{T}$.Answer:D. Newton per ampere meter