A solenoid has a density of 1000 turns per meter and carries a current of 2 A. What is the magnetic field inside the solenoid?

easy 1 mark Class 12 · Physics · Magnetism and Matter

Answer

2.51×10⁻³ T

The correct answer is 2.51×10⁻³ T — Therefore the magnetic field inside the solenoid is $2.51 \times 1 0^{- 3}; T$ .

Step-by-step solution

Compute the turn density $n$ : $n = 1000; turns/m$ .
Write the formula for the magnetic field inside a long solenoid: $B = μ_{0}, n, I$ , where $μ_{0} = 4 π \times 1 0^{- 7}; T\cdotm/A$ .
Substitute the given values: $B = (4 π \times 1 0^{- 7}) (1000) (2); T$ .
Simplify: $(4 π \times 1 0^{- 7}) \times 2000 = 2.513 \times 1 0^{- 3}; T$ .
Round to three significant figures: $2.51 \times 1 0^{- 3}; T$ .
Therefore the magnetic field inside the solenoid is $2.51 \times 1 0^{- 3}; T$ .

Common mistake: Using an incorrect value for

m u_{0}

or forgetting the unit of

n

Concept tested: Magnetic field inside solenoid

Published 9 September 2026 · Last updated 16 September 2026 · How this solution was prepared and checked