sci_phy
Reflection and Refraction
Chapter summary, hard words and model exam answers for ICSE Class 10 Hindi.
Free online summary and notes (ICSE Class 10 Hindi). Read it here, no PDF download needed.
About the author
Physics · CBSE 10 · ICSE 10 · GCSE (AQA, Edexcel, OCR)
Summary
Both angles are measured from the normal. A plane mirror gives an upright, same-size, laterally inverted image as far behind the mirror as the object is in front.
Entering a denser medium (air to glass) it slows and bends toward the normal. Leaving into a less dense medium it speeds up and bends away.
A bigger n means slower light and more bending. Snell's law links the two angles: n1 sin(theta1) = n2 sin(theta2).
Conditions: light goes dense to less dense, and the angle exceeds the critical angle (sin C = 1/n). Used in optical fibres and diamonds.
Hard words & meanings
| normal | An imaginary line at 90 degrees to a surface at the point a ray strikes it. |
| angle of incidence | The angle between the incoming ray and the normal. |
| reflection | Light bouncing off a surface so that the angle in equals the angle out. |
| refraction | The change in direction of light as it changes speed crossing into a new medium. |
| refractive index (n) | How much slower light travels in a medium than in vacuum: n = c/v. |
| Snell's law | n1 sin(theta1) = n2 sin(theta2), relating the angles to the refractive indices. |
| critical angle | The angle of incidence in a denser medium beyond which total internal reflection occurs (sin C = 1/n). |
| total internal reflection | Complete reflection of light back into a denser medium when the angle exceeds the critical angle. |
Model exam answers, grammar & audio
You have read the summary. The board-ready model answers, grammar notes, one-touch audio and writing practice for this chapter are part of Lipi©.
Sign in to unlockSee it, understand it, hear it read aloud, then write the exam answer with confidence, for a fraction of a tutor cost.