Answer and Explanation:
Parallax method is used for finding the distance of objects in space there are two types of parallax method that is stellar parallax and trigonometric parallax.The disadvantage of using parallax method is that it can can not reach so far in the Galaxy due to this reason parallax method is generally not used for measuring distance in galaxy.
Answer:
The diameter of wire should be
m
Explanation:
Given:
Current density

Current
A
From the formula of current density,

Where
area of cylindrical wire = 



m
For finding the diameter of wire,

m
Therefore, the diameter of wire should be
m