Question

Lemon kept in a glass of water looks bigger, why?

Answer 1

Hint: We are able to see because of the light. If there is no light such as in a dark room, we cannot see anything. Light after striking the objects gets reflected and they come into our eye, the lens converges them and a picture is formed onto the retina. Light travels in a straight line but whenever there is a change of medium then the path of the light rays changes their directions as evident from the concept of refraction.

Complete answer:
Refraction of light is a phenomenon in which light when it moves from one medium to another then its direction of propagation changes, its wavelength and speed may also change but the frequency remains the same. The point of incidence at the plane which separates the two media, a perpendicular line is drawn called normal. The angle of incidence and the angle of refraction all are made by the light rays with the normal. When light moves from rarer medium to denser medium it moves towards the normal and when it moves from denser medium to a rarer medium it moves away from the normal. Since the lemon is kept in the glass and light rays move from water to air that is from denser medium to a rarer medium, they move away from the normal and due to this refraction phenomenon, the lemon appears larger to the observer.

Note:
If a light ray is incident obliquely perpendicular to the surface separating the two media, the light ray passes undeflected without any change in its direction. Thus, a point size object when seen placed inside the glass containing water, appears to be of the same size as the light rays passing undeflected.