5H10.17 • Magnetic Fields: Dip Needle + Oersted's Apparatus

Photo shows the demonstration used at the University of Texas at Austin.

left: no current; right: 1.26 A inputted

---

Concepts Conveyed:

• Earth's magnetic field can be used to find the dip angle.
• Current loop produces a magnetic field.

---

Instructions:

• Dip angle: align the horizontal compass needle with the Earth's magnetic field, then rotate it to vertical to show the angle of where the field points into/out of the horizontal plane.
• Current loop: DC power supply runs a current through the aluminum frame. The needle will deflect in response to the magnetic field that is produced by this current. A noticable deflection will occur between 1-2 A.

---

Demo Staff:

• Align the compass needle with Earth's field before the class starts.
• Connect the apparatus to the DC power supply.

Last updated on November 6, 2025