(a) What is meant by refraction of light ?
(b) If on applying Cartesian sign convention for spherical lenses the image distance obtained is negative, state the significance of the negative sign.
(a) When light travels obliquely from one medium to another, the direction of propagation of light in second medium changes. This phenomenon is known as refraction of light.
(b) Negative sign of image distance means the image is virtual and erect and is formed on the same side of the object with respect to the lens.