# [Magnetism] Tricky task on self-inductance of solenoid

**1. The problem statement, all variables and given/known data**

Problem:

A Solenoid has N turns of Copper wire (Cross-section area of the wire is 10

^{-6}m

^{2}) The Length of the solenoid is 25*10

^{-2}m and its Resistance is 0.5 Ω. What’s the Self-Inductance of the solenoid?

**2. Relevant equations**

Given answer: 5.5*10^{-5} H

Please help me with the solution.

**3. The attempt at a solution**

How do you relate Resistance with Self-inductance to eliminate the need for (or find) the number of turns? All I could find by using R was the length of the whole wire(an unrolled solenoid). But this gives me nothing on the number of turns cause the diameter of the solenoid is not given.

http://ift.tt/1jHLmqu

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