Magnetic Effects of Current and Magnetism Part 1

Given, magnetic field at the centre at A is 3T.
Since, the solenoid B,C and D are connected in parallel arrangement. We know that,
The magnetic field in the circuit is directly proportional to the
B∝i
⇒‌‌‌

BA

BC

=‌

IA

IC

⇒‌

3T

BC

=‌

i

i∕3

⇒‌‌BC=1T
So, the field at the centre at C=1T.