ICSE Class 10 Answered

If rays enter from glass to air it bends towards the nomal What causes the bending of ray when it treaels from glass to air

Asked by vinitadwivedi13 | 18 Dec, 2022, 03:14: PM

Expert Answer

When light ray refracts from a medium of low refractive index to high refractive index ,

light ray bends towards normal drawn at the point of incidence as shown in figure.

(Refractive index of glass is greater than refractive index of air )

When light ray refracts from a medium of high refractive index to low refractive index ,

light ray bends away from normal drawn at the point of incidence as shown in figure.

This phenomenon is explained using the concept of Hygen's wave theory .

As shown in figure, when wavefront AB incident on air-glass interface , point A will travel further with higher speed

inside glass but the point B will travel faster in air . This speed difference between the wavefront ends

makes the wavefron to bend towards normal inside glass .

As shown in figure, when wavefront EF incident on glass-air interface , point F will travel further with low speed

in air but the point E will travel slower in glass . This speed difference between the wavefront ends

makes the wavefron to bend away from normal inside glass .

Answered by Thiyagarajan K | 18 Dec, 2022, 03:48: PM