Answer:
L= 12 light years
Explanation:
for length dilation we use the formula

now calculating Lo
Lo = 12.5×365×24×3600×3×10^8
= 1.183×10^17 m
now putting the values of v and Lo in the above equation we get

= 1.136×10^17 m
L=
m
so L= 12 light years
Hope this shows! It has all the equations for all of the problems u asked in the comments
Answer:
magnification will be -0.025
Explanation:
We have given the radius of curvature = 12 cm
And object distance = 3 m
So focal length 
Now for mirror we know that
So 

v = 0.750 m
Now magnification of the mirror is 
Electricity is a form of energy. Electricity is the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons. Hope this helped. ;)