# a solenoid of length 50 cm with 20 turns per cm and area of cross section 40 cm2 completely surrounds another coaxial solenoid of the same length , area of cross section 25 cm2 with 25 turns per cm . calculate the mutual inductance of the system ?

here,          l=50 cm=0.05m
N1=20    ,N2=25 ,A1=40 cm2  ,A2=25cm2
now

we know,         M1=4*3.14*10-7N1 N2A1 l    & M2=4*3.14*10-7N1N​2A2l
therefore         ,add both M1 &  M2
​NOW, find  Mtotal and we will get answer
i think you will better understand it !!!!!!!!!!!!!!

• -3