A length of conducting wire is bent into a circular coil of 4 turns. The diameter of the circle is 30.0 cm, and the axis of the coil is perpendicular to the horizontal component of the Earth's magnetic field. A horizontally-oriented compass is placed along the axis of the coil, directly in the center, and when a current of 0.690 A flows in the coil, the compass needle is deflected by 45° from magnetic north. (a) What is the horizontal component of the Earth's magnetic field at this location (in µT)? (B) The current in the coil is switched off. A "dip needle" is a magnetic compass mounted so that it can rotate in a vertical north-south plane. At this location, a dip needle makes an angle of ϕ = 21.0° from the vertical. What is the total magnitude of the Earth's magnetic field at this location (in µT)?

A length of conducting wire is bent into a circular coil of 4 turns. The diameter of the circle is 30.0 cm, and the axis of the coil is perpendicular to the horizontal component of the Earth's magnetic field. A horizontally-oriented compass is placed along the axis of the coil, directly in the center, and when a current of 0.690 A flows in the coil, the compass needle is deflected by 45° from magnetic north. (a) What is the horizontal component of the Earth's magnetic field at this location (in µT)? (B) The current in the coil is switched off. A "dip needle" is a magnetic compass mounted so that it can rotate in a vertical north-south plane. At this location, a dip needle makes an angle of ϕ = 21.0° from the vertical. What is the total magnitude of the Earth's magnetic field at this location (in µT)?