Galaxies are much further apart than stars. This is the reason why they are less likely to collide and the likelihood of galactic collision is much smaller than the likelihood of stellar collision. Example for galaxy collision is the collision of the Milky Way galaxy with Andromeda. It is estimated that the collision will be <span>in about 4.5 billion years. </span>
Answer:

Explanation:
given,
refractive index of lens, n = 1.70
Radius of curvature of front surface. R₁ = 20 cm
Radius of curvature of the back surface, R₂ = 30 cm
focal length= ?

R₁ = +20 cm
R₂ = -30 cm
n = 1.70




the focal length of the lens is equal to 17.15 cm
Answer:
Image distance of apple=-6.7 cm
Magnification of apple=0.33
Explanation:
We are given that an apple is placed 20.cm in front of a diverging lens.
Object distance=u=-20 cm
Focal length=f=-10 cm
Because focal length of diverging lens is negative.
We have to find the image distance and magnification of the apple.
Lens formula

Substitute the values then we get




Image distance of apple=-6.7 cm
Magnification=m=
Magnification of apple=
Hence, the magnification of apple=0.33
Vapor is usually made with water and it would be made with gas.