A 15-g 10-cm-long wire is suspended horizontally between the poles of a horseshoe magnet. The magnetic field is horizontal between the poles of the magnet where the wire is suspended. When the 0.50-A current in the wire is turned on, the wire jumps up and out of the magnet. Draw the situation, carefully indicating the direction of the current and the field. What is the minimum magnetic field created by the horseshoe magnet?

Your answer is 120miles 

How is it possible that phylogenies based on sequences from nuclear genomes and organellar genomes (i.e., chloroplasts and mitochondria) from the same group of species yield phylogenetic trees with different branching orders?   answer :   the genome of the endosymbiont is more closely related to members of the group in which it originally evolved, while the nuclear genome of the engulfing organism has its own evolutionary trajectory.