A long, straight, horizontal wire carries a left-to-right current of 20 a. If the wire is placed in a uniform magnetic field of magnitude 4. 0\times 10^{-5}~\text{t}4. 0×10 −5 t that is directed vertically downward, what is the resultant magnitude of the magnetic field 20 cm above the wire?.

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.