This document contains important theory questions about refraction of light at a plane surface and total internal reflection. It includes 24 multiple choice and derivation questions covering topics such as Snell's law, refractive index, critical angle, total internal reflection, mirages, reflecting prisms, reversing prisms, erecting prisms, optical fibers, and their applications. The document was prepared by Mukesh N Tekwani and provides a comprehensive review of key concepts and formulas relating to the refraction and total internal reflection of light.

1. IMPORTANT THEORY QUESTIONS
Refraction of Light at a Plane Surface : Total Internal Reflection
Prepared by : Mukesh N Tekwani
Email: scitechgen@outlook.com
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1 Define the term ‘refraction of light’ 1 Define
2 State the laws of refraction. 2 Laws of
refraction
3 State Snell’s law of refraction and give the equation relating refractive index
with angle of incidence and angle of refraction.
3 Snell’s law
4 Why does refraction of light occur? 1 Refraction
5 What information do we get from the refractive index of a material? 2 RI
6 What is the SI unit of refractive index? Explain your answer. 1 SI unit
7 State the principle of reversibility of light. Draw a neat ray diagram to
explain this concept.
2 Reversibility of
light.
8 If 1n2 and 2n1 are the refractive indices of medium 2 relative to medium 1,
and medium 1 relative to medium 2 respectively, then what is the relation
between 1n2 and 2n1?
1 Formula
9 Derive an expression for the refraction of light passing through multiple
media like air, water, glass and back into air.
5 Derive
10 For refraction through parallel multiple media, show that 1n3 = 1n2 x 2n3 5 Derive
11 Define ‘real depth’ and ‘apparent depth’ Illustrate these terms with a neat
diagram.
2 Define,
diagram
12 Define ‘critical angle’ and ‘total internal reflection’ 2 Define
13 State the two conditions that must be fulfilled for total internal reflection to
occur.
2 TIR
14 Obtain the relation between refractive index and critical angle. Assume
Snell’s law equation.
2 Derive
15 What is a mirage? Explain. 2 Mirage
16 Explain, with neat ray diagram, the construction and working of a simple
reflecting prism.
3 Reflecting
Prism
17 Explain, with neat ray diagram, the construction and working of a reversing
prism.
2 Reversing
Prism
18 Explain, with neat ray diagram, the construction and working of an erecting
prism.
2 Erecting Prism
19 State the advantages of totally reflecting prisms over plane mirrors. 2 Prisms
(c)M
ukesh
N
Tekw
ani

2. © Mukesh N Tekwani (scitechgen@outlook.com)
20 Why does a diamond sparkle brilliantly when seen along certain directions? 2 TIR
21 State the names of three types of totally reflecting prisms. What are the
advantages of these prisms over a plane mirror?
2 Prisms
22 Describe the construction, working and principle of operation of an optical
fibre.
5 Optical fibre
23 State any three applications of optical fibres. 3 Optical fibre
24 Explain refraction of light and write its laws. Derive the relation n = Real
depth / Apparent depth
5 Derive
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(c)M
ukesh
N
Tekw
ani