Activity 2: Magnetic Field due to an Electromagnet Open the Magnets and Electromagnets simulation. Select the Electromagnet tab and explore it. Select the DC current source, and use the slider to increase its emf to 10 V. For the number of loops, select 1. Also check the Show Field, Show Compass, and Show Electrons boxes. 15. Move the compass to several positions around the coil. Based on your observations, list a few similarities between a bar magnet and a coil