Question

A solenoid of 1.5 m length and 4.0 cm diameter possesses 10 turns/cm. A current of 5 A is flowing through it. The magnetic induction at axis inside the solenoid is

• A. $2 \pi \times 10^{-3}T $
• B. $2 \pi \times 10^{-5}T $
• C. $2 \pi \times 10^{-3}G $
• D. $2 \pi \times 10^{-5}G $

Answer 1

The Correct Option is A

Magnetic field B \(= \mu _0ni\)
\(h\,space\.15mm =4 \pi \times 10^{-7} \times 5 \times 1000\)
\(h\,space\,\,15mm = 2 \pi \times 10^{-3} T\)

Answer 2

n = 10 turns/cm = 1000 turns/meter
I=5 A
magnetic induction inside solenoid = B = μonI
∴  B = 4π × 10^–7 × 1000 × 5
= 2π × 10^–3 T