a brass rod of length 0.40 cm and steel rod of length 0.60cm, both are initially at 0 degree celsius are heated to 75 degree celsius. if the increase in length is the same for both the rods, calculate the linear expansivity of brass. given alpha for steel is 12*10 power -6​

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.