Author Question: How are the Tully-Fisher calculations for the distance to a galaxy different from those used for ... (Read 165 times)

clippers! · **on:** Jul 28, 2018

How are the Tully-Fisher calculations for the distance to a galaxy different from those used for spectroscopic parallax?

Question 2

Rank the magnitudes of the following magnetic fields from largest to smallest, noting any cases of equality.
(a) the field 2 cm away from a long, straight wire carrying a current of 3 A
(b) the field at the center of a flat, compact, circular coil, 2 cm in radius, with 10 turns, carrying a current of 0.3 A
(c) the field at the center of a solenoid 2 cm in radius and 200 cm long, with 1 000 turns, carrying a current of 0.3 A
(d) the field at the center of a long, straight, metal bar, 2 cm in radius, carrying a current of 300 A
(e) a field of 1 mT

1.a > e > b > d > c
2.e > d > b > c > a
3.e > c > b > a > d
4.e > c > b > a > d
5.b > c > d > a > e

alexanderhamilton · **Reply #1 on:** Jul 28, 2018

Answer to Question 1

Since we are still using the apparent and absolute brightness measurements the
calculations are the same but here we are using another independent variable to
determine the absolute brightness.

Answer to Question 2

4