What information can be determined by observing dark lines within the spectrum of a given star?
a. the elements present in the star's atmosphere
b. the elements present in the star's inner core
c. whether planets orbit the star
d. the approximate size of the star

The magnitude of the magnetic field at a certain distance from a long, straight conductor is represented by b. what is the magnitude of the magnetic field at twice the distance from the conductor? a. at twice the distance, the magnitude of the field is 4b.b. at twice the distance, the magnitude of the field is 2b.c. at twice the distance, the magnitude of the field is b/2.d. at twice the distance, the magnitude of the field is b/4.e. at twice the distance, the magnitude of the field remains equal to b.