It is known that the magnitude of the magnetic field created by a Helmholtz coil is proportional to the current passing through it. For the coils used in our experiment set, the proportionality constant between the magnetic field and current was found to be k = 6.73 x 10 T/A. The direction of the horizontal component of the Earth's magnetic field was found with the compass and a vertical field was created with the coil. It was observed that the compass needle deviated 71 from the initial position when 80mA of current was passed through the coils. What is the value of the horizontal component of the Earth's magnetic field (in T)? a. 20.2 . 15,3 O c. 12.0 d. 37.0 Oe. 18.5