Q. Which of the following is equivalent to tesla ?
a) Ampere per Newton
b) Newton per Coulomb
c) Newton per ampere-second
d) Newton per ampere meter
Question from BPSC PT 70, 2024
Correct Answer: d) Newton per ampere meter
Explanation:
The tesla (T) is the SI unit of magnetic flux density (or magnetic field strength). It is defined as the magnetic flux density that produces a force of one newton (N) on a one-meter-long conductor carrying a current of one ampere (A) perpendicular to the magnetic field.
From the Lorentz force law, the force F on a current-carrying conductor in a magnetic field is given by:
F = B · I · L · sinθ
Where:
– F is the force in newtons (N),
– B is the magnetic flux density in teslas (T),
– I is the current in amperes (A),
– L is the length of the conductor in meters (m),
– θ is the angle between the conductor and the magnetic field.
Rearranging for B, when sinθ = 1 (perpendicular field):
B = F / (I · L)
The unit of B (tesla) can thus be expressed as:
1 T = N / (A · m)
This matches option d) Newton per ampere meter.
