A long solenoid has 200 turns per cm and carries a current i. The magnetic field at its centre is 6.28 × 10–2 weber/m2. Another long solenoid has 100 turns per cm and it carries a current i/3. The value of the magnetic field at its centre is
(a) 1.05 × 10–4Wb/m2
(b) 1.05 × 10–2Wb/m2
(c) 1.05 × 10–5Wb/m2
(d) 1.05 × 10–3Wb/m2 .
