g The sun's rays are focused, using a lens as a "burning glass." All the visible sunlight entering a lens of radius 2.70 cm is concentrated in a circular spot of radius 0.950 mm. Find the intensity of visible light in the spot if the intensity of visible light striking the lens is 777 W/m2.

I'm thinking it's 2 you are asked to explain the earth's magnetic field. which is the best reply? 1. the earth's magnetic south is similar to the north pole of a magnet. 2. the earth's core has a strong magnetic charge similar to the south pole of a magnet. 3. the earth's geomagnetic south is similar to the south pole of a magnet. 4. the earth's magnetic charge is not centered at either pole; it varies based on location.