Question

Q4 e) pls ans fast and give reason and ans in proper form

I will mark it as brainliest

Answer 1

2.power of lens is defined as 1/focal length means power of lens is inversely proportional to focal length.
3.. - sign because a person cannot se far of object so we prefer concave lens (- sign) and same as positive sign..
I'm not in class 10 so i do not know about prism effect .. i hope this two answer make effective

Answer 2

the reciprocal of the focal length is known as power of lens..
the positive power means that lens is convex.
and the negative power means the lens is concave..

The index of refraction must decrease across the boundary in the direction of light refraction.

The angle of incidence of the light ray must exceed the critical angle of the interface.
Beacuse prism provides the spectrum which plane mirror don't show... That's it.. Thanks
Hope it help you....