A long solenoid has a radius a and number of turns per unit length n. If it carries a current i, then the magnetic field on its axis is directly proportional to
A. ani
B. ni
C. ni /a
D. n2i
Answer:B
A long solenoid has a radius a and number of turns per unit length n. If it carries a current i, then the magnetic field on its axis is directly proportional to
A. ani B. ni C. ni /a D. n2i