HC Verma Photometry Solutions (Chapter 22)

HC Verma Concepts of Physics Part 1 Solutions for Chapter 22 ‘Photometry’ reveal the concepts behind a light source able to produce visible light or luminous efficiency. It is an interesting chapter in HC Verma Class 11 Physics Solutions. Studying the chapter, you will get familiar with various important concepts of Photometry like  Lambert’s Cosine Law. You will understand how the brightness of the light is related to its wavelength and how illuminance on a particular surface can be increased or decreased.

HC Verma Photometry Chapter has around 4 exercises with a total of 38 exemplar problems based on radiant flux, illuminance, photometers, relative luminosity, and luminous flux of source. There are different types of questions available for practice including short answer type questions, long answer type questions, and objective-type questions. Our HC Verma Physics Part 1 Photometry Solutions will prove to be essential for learning and building the concepts of this chapter for exams.

While some questions are difficult to understand on the first go. At Instasolv, we always try our best to provide step-by-step solutions for the exercise questions to you. Practising these questions and answers will help you to score high marks in CBSE Class 11 Physics exams as well as in competitive exams like JEE, NEET, and more. You can follow the HC Verma Concepts of Physics Part 1 Photometry Solutions provided by Instasolv from anywhere and at any time.

Important Topics for HC Verma Concepts of Physics Part-1 Solutions Chapter 22: Photometry

Total Radiant Flux

The total radiant flux is the radiant energy produced, transmitted, reflected or received, per unit time, and spectral power is the radiant flux per unit wavelength or frequency, depending on whether the spectrum is taken as a function of wavelength or of frequency.

The radiant flux is measured in watt but the SI unit of spectral flux in frequency in the watt per hertz (W/Hz) and the SI unit of spectral flux in wavelength id the watt per metre (W/m).

The luminosity of Radiant Flux

The luminous flux is equal to the total wavelength- weighted power produced by a source. The luminous flux is like luminosity and it is calculated in the lumen (lm), which is equal to the candela-steradian (

Luminous Efficiency

The percentage of the amount of light produced by the luminaire to the amount of light produced by its lamps is known as luminous efficiency. The SI unit of luminous efficiency is measured in lumen per watt (lm/W).

Lambert’s Cosine Law

Lambert’s Cosine Law states that when light falls diagonally on the surface, the illumination of the surface is directly proportional to the cosine of the angle among the direction of the surface normal and the incident light. Lambert’s cosine law is also called the lambert’s emission law or cosine emission law.


An instrument that measures the strength of electromagnetic radiation in the range from ultraviolet (UV) to infrared (IR) and containing the visible spectrum is known as a photometer. A  photometer converts light into the electric current utilizing photodiode, photomultiplier, or a photoresistor.


The total luminous flux incident on a surface per unit area is known as illuminance. Illuminance is a measure of how much the incident light lightens the surface, wavelength- weighted by the luminosity function to compare with human brightness approach. The SI unit of illuminance is lux (lx).

Exercise-wise Discussion for HC Verma Concepts of Physics Part-1 Solutions Chapter 22: Photometry

Exercise 1 – Short Answer Type Questions

This exercise has around 7 questions that are completely related to the concept that deals with the angular dispersion of rays reliant upon the locating of the prisms whether it is in the same way directed or oppositely directed.

Exercise 2 – Objective Type Questions I

The first exercise of the chapter has around 11 questions which are multiple-choice questions. These questions are based on luminous efficiency, illuminance, photometers, and Lambert’s Cosine Law.

Exercise 3 – Objective Type Questions II

This exercise has around 4 questions in which you need to choose the right answer from the options given. They can have two or more than two options correct.

Exercise 4 – Long Answer Type Questions

This exercise set has a total of 16 questions which are long answer type questions and you need to provide a detailed explanation in these questions. 

Why Use HC Verma Concepts of Physics Part-1 Solutions Chapter 22: Photometry by Instasolv?

  • Refer to our HC Verma Concepts of Physics Part 1 Solutions for Photometry anytime you have a doubt in the chapter. 
  • We have provided detailed solutions for all the questions available in the chapter that will make it easier for you to understand the topics. 
  • With the help of our HC Verma Solutions, you can save time especially during exam time and while doing a revision of the chapter. 
  • All the solutions are prepared by the expert Physics teachers who are well-versed with the CBSE Class 11 exam pattern and guidelines.
  • These solutions will help you prepare for the CBSE exams as well as the competitive exams like NEET and JEE. So, follow them now for free!