How Is Ampere's Law Applied to Calculate Magnetic Fields?

[This Is Me]

Homework Statement

What is the magnitude of a magnetic field from a 3.5 cm straight conductor with a current of 1.8 A?

Relevant Equations

∫B.dl = μ0I

(I accidentally missed my lesson and I don't know how to apply this question to the formula)

 

[berkeman]

Welcome to PF.

Even if you missed the lesson, you need to show some effort before we can offer tutorial help. What have you found in your searching so far? Have you looked this up on Hyperphysics? Have you read over the lesson notes? Which textbook are you using?

 

[This Is Me]

Welcome to PF.

Even if you missed the lesson, you need to show some effort before we can offer tutorial help. What have you found in your searching so far? Have you looked this up on Hyperphysics? Have you read over the lesson notes? Which textbook are you using?

I got some help, thanks though.

 

[kuruman]

I got some help, thanks though.

I cannot imagine what kind of help you got. The statement of the problem is

Homework Statement:: What is the magnitude of a magnetic field from a 3.5 cm straight conductor with a current of 1.8 A?

To me, it says that you have a conductor, most likely a wire, that is 3.5 cm long which carries a current of 1.8 A. In that case, Ampere's law is not applicable and you have to (a) use the law of Biot-Savart and (b) know where in space the magnitude of the field is to be calculated. Another interpretation could be that the conductor is a very long wire (not explicitly mentioned in the statement) and the point of interest is at a distance of 3.5 cm from it (also not explicitly stated).