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## Homework Statement

There are two coaxial solenoids, each 30cm long. One is inside the other. Each carry a current of 3A, but in opposite directions. Inner solenoid has a radius of 3cm and the outer has a radius of 6cm. Inner has 15 turns/cm and the outer has 30 turns/cm. Find the magnitude and direction of the magnetic field inside the solenoid, between the inner and outer solenoids, outside the outer most solenoid. What is the inductance of the inner solenoid? The outer?

## Homework Equations

B=(uNI)/l

## The Attempt at a Solution

B due to the outer solenoid turns out to be 360piX10^-5 T and for the inner it is 180piX10^-5 T So for the magnetic field in the inner solenoid it would be the difference between the two fields since they are going in the opposite direction. THis makes it 180piX10^-5 T in the direction that the outer solenoid dictates. How do I get the field between them and outside the oter most solenoid? Thanks.