Detailed Study:

Frequently Tested Topics:

  • Applications of various radiations in spectrum

  • Wavelengths of various radiations in spectrum

  • Give reasons based on scattering of light

  • Definition of scattering

*Note that other aspects of the chapter are equally important.

Important Past Questions:

  • An electromagnetic radiation is used for photography in fog.

i) Identify the radiation.

ii) Why is the radiation mentioned by you ideal for this purpose? 

(2007, 2013, 2019)

  • Define scattering.

(2018, 2016)

  • Which colour of light is scattered the least and why?

(2012, 2016)

  • 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


  • Name the high energetic invisible electromagnetic waves which help in the study of the structure of crystals. State an additional use of the waves mentioned by you. 

(2007, 2015)

  • Name a prism required for obtaining a spectrum of ultraviolet light.


  • Name the radiations which can be detected by a thermophile.


  • Why is the colour red used as a sign of danger?


  • What is meant by dispersion of light?


  • Which characteristic property of light is responsible for the blue colour of the sky?


  • Why is white light considered to be polychromatic in nature?


  • Give the wavelength range of those electromagnetic waves which are visible to us. 


  • Why does the sun appear red at sunrise?


  • Name the subjective property of light related to its wavelength.


  • Name the radiations:

i) that are used for detection of fracture in bones

ii) whose wavelength range is from 100 Å to 4000 Å (or 10nm to 400nm)


  • Suggest one way in each case by which we can detect the presence of:

i) Infra red radiations

ii) Ultraviolet radiations.


  • Give one use of infra red radiations. 


  • A type of electromagnetic wave has wavelength 50 Å.

i) Name the wave.

ii) What is the speed of the wave in vacuum?

iii) State one use of this type of wave.