sci_phy
Refraction of Light
Chapter summary, hard words and model exam answers for Class 10 Hindi.
Free online summary and notes (Class 10 Hindi). Read it here, no PDF download needed.
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Physics · ICSE Class 10
Summary
The bending happens because the speed of light changes in the second medium. If light enters normally, speed changes but direction does not bend.
The constant ratio is called refractive index for the pair of media. This is Snell's law in the form needed for ICSE.
When light goes from rarer to denser medium, it bends towards the normal. From denser to rarer, it bends away from the normal.
A higher refractive index means lower speed of light in that medium and usually greater bending for the same boundary.
If the angle of incidence in the denser medium is greater than the critical angle, total internal reflection occurs. Optical fibres and sparkling diamonds use this effect.
Hard words & meanings
| refraction | Change in direction of light due to change in speed at a boundary |
| normal | Line perpendicular to the surface at the point of incidence |
| refractive index | Ratio showing how much a medium slows light |
| optically denser | Medium in which light travels slower |
| critical angle | Angle of incidence in denser medium for which angle of refraction is 90 degrees |
| total internal reflection | Complete reflection back into denser medium when incidence angle exceeds critical angle |
Model exam answers, grammar & audio
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