Complete the path of the ray AB through the glass prism in PQR till it emerges out of the prism. Given the critical angle of the glass as 42 ° .

When the ray of light enters the triangular prism from point B it goes undeviated at it is falling normally to the surface. . When the ray reaches the glass-air interface, due to the angle of incidence being greater than the critical angle i.e., 42 ° hence, it will suffer total internal reflection inside the prism and will travel in the direction CD as shown in the figure. The angle of incidence at D can be found by considering the quadrilateral BCDQ (sum of all internal angles of a quadrilateral is 360 ° ).

Scattering of light occurs when light rays collide with an obstruction such as dust, gas molecules, or water vapours and divert from their straight path. Scattering is the process of absorption and then re-emission of light energy. Blue colour of the sky in daytime is due to the scattering of light.

Why is the ratio of the velocities of light of wavelengths 4000 Å & 8000 Å in vacuum 1 : 1 ? Which of the above wavelengths has a higher frequency?

The velocity of light is always constant in vacuum. The velocity of light in vacuum is 3 × 10 8 m s and it does not depend on wavelength or frequency of the wave. We know that, c = ν λ ⇒ ν = c λ ⇒ ν ∝ 1 λ Frequency is inversely proportional to the wavelength, so the wave with wavelength 4000 Å will have higher frequency.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 6 - Electromagnetic Spectrum and Dispersion of Light>ICSE-2018>Q 5

MEDIUM

10th ICSE

IMPORTANT

Earn 100

The smoke from a fire looks white. Which of the following statements is true?
(1) Molecules of the smoke are bigger than the wavelength of light.
(2) Molecules of the smoke are smaller than the wavelength of light.

Important Questions on Electromagnetic Spectrum and Dispersion of Light

MEDIUM

10th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 6 - Electromagnetic Spectrum and Dispersion of Light>ICSE-2019>Q 6

An electromagnetic radiation is used for photography in fog.
(i) Identify the radiation.
(ii) Why is this radiation mentioned by you, ideal for this purpose?

HARD

10th ICSE

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR SCIENCE>Chapter 6 - Electromagnetic Spectrum and Dispersion of Light>ICSE-2019>Q 7

How does the angle of deviation formed by a prism change with the increase in the angle of incidence? Draw a graph showing the variation in the angle of deviation with the angle of incidence at a prism surface.