What shape are the magnetic field lines around a long straight current-carrying wire?

State the magnetic field magnitude at distance \(r\) from a long straight wire carrying current \(I\).

A vertical wire carries current upward. At a point to the right of the wire, is the magnetic field into or out of the page?

Find the magnetic field \(0.040\,\mathrm m\) from a long straight wire carrying \(10\,\mathrm A\).

A long straight wire carries \(8.0\,\mathrm A\). At what distance is the magnetic field \(4.0\times10^{-5}\,\mathrm T\)?

Two identical long parallel wires carry equal currents in the same direction. What is the net magnetic field at the point halfway between them?

Two long vertical wires are \(0.20\,\mathrm m\) apart and both carry upward current. The left wire carries \(5.0\,\mathrm A\) and the right wire carries \(3.0\,\mathrm A\). Find the net field at the midpoint.

Two identical long wires carry equal currents in opposite directions. What happens to the magnetic field at the midpoint between them?

Use Ampere's law to derive the long-straight-wire field magnitude.

A wire's current is tripled and the observation distance is doubled. By what factor does the straight-wire magnetic field change?