A long solenoid of radius 1 mm has 100 turns per mm. If 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is :

Question

A long solenoid of radius 1 mm has 100 turns per mm. If 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is : (A) 6.28 × 10-4 T (B) 6.28 × 10-2 T (C) 12.56 × 10-2 T (D) 12.56 × 10-4 T

Tardigrade Admin · Accepted Answer

B =μ0 ni =μ0 ( N /ℓ) i ∴ B =4 π × 10-7 × (100/10-3) × 1 =12.56 × 10-2 T

Q. A long solenoid of radius $1 mm$ has $100$ turns per $mm$ . If $1 A$ current flows in the solenoid, the magnetic field strength at the centre of the solenoid is :

$6.28 \times 1 0^{- 4} T$

$6.28 \times 1 0^{- 2} T$

$12.56 \times 1 0^{- 2} T$

$12.56 \times 1 0^{- 4} T$

$B = μ_{0} ni = μ_{0} \frac{N}{ℓ} i$
$∴ B = 4 π \times 1 0^{- 7} \times \frac{100}{1 0 ^{- 3}} \times 1$
$= 12.56 \times 1 0^{- 2} T$

Q. A long solenoid of radius 1mm has 100 turns per mm. If 1A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is :

6.28×10−4T

6.28×10−2T

12.56×10−2T

12.56×10−4T