To get an idea of the order of magnitude of inductance, calculate the self-inductance in henries for a solenoid with 900 loops of wire wound on a rod 6 cm long with radius 1 cm?

The  self-inductance is  

Explanation:

From the question we are told that  

      The number of loops is  

      The  length of the rod is  

      The radius of the rod is  

The  self-inductance for the solenoid is mathematically represented as

Now the cross-sectional of the solenoid is mathematically evaluated as

substituting values  

and   is the permeability of free space with a value  

    substituting values into above equation

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

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