Question

Why is pencil immersed under water appears to be bent ?

Answer 1

A stick or a pencil half immersed in water at an angle appears bent due to refraction of light at the air-water surface. Figure shows a straight stick AO whose lower portion BO is immersed in water. It appears to be bent at point B in the direction BI. A ray of light OC coming from the lower end O passes from water into air at C and gets refracted away from the normal (light going from denser to rarer medium deviates away from normal) in the direction CX.Another ray OD gets refracted in the direction DY. The two refracted ray CX and DY, when produced backward, appear to meet at point I, nearer to the water surface than O. Similarly each part of the immersed portion of the stick forms raised image. As a result immersed portion of the stick appears to be bent when viewed at an angle from outside.