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A solenoid has a fixed total number of turns N and a fixed cross-sectional area A, but its length L can be changed by adjusting the spacing between windings. How does its self-inductance depend on L?
- proportional to 1/L²
- proportional to 1/L
- proportional to L
- proportional to L²
Correct answer: proportional to 1/L
Solution
The inductance of a solenoid is L_ind = mu0*N²*A/(length). With N and A held constant, L_ind is inversely proportional to the length. So as length L increases, inductance decreases as 1/L.
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