Solenoid Field Strength - Missing Raduis?

AI Thread Summary
The discussion revolves around calculating the magnetic field strength inside a long solenoid with 35 turns per centimeter and a current of 4.0A. Participants note that the formula provided, which includes a radius, is not applicable to long solenoids. Instead, they suggest using Ampere's law to derive the magnetic field strength, which is expressed as B = μ₀ i n, where n represents the turns per unit length. The absence of the radius in the problem statement is highlighted as a key issue. Ultimately, the correct approach focuses on the solenoid's characteristics rather than the circular coil formula.
Euler2718
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Homework Statement



A long solenoid has 35 turns/cm. With a current of 4.0A, what is the field strength at the core?

Homework Equations



\beta = \frac{\mu N I}{2r}

The Attempt at a Solution



I have no idea with the radius is; that's the entire problem statement above.
 
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The formula you gave is for a circular coil of short length. A different formula applies to the long solenoid. Check your notes or textbook.
 
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Using Ampere's law, we can derive the magnetic field inside a solenoid. It is B = u_o i n, where n is turns/length
 
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