NCERT Solutions for Class 11 Physics Chapter 15
NCERT Solutions for Class 11 Physics Chapter 15 – Waves
A wave is a quivering disruption that travels across a medium due to the regular motion of particles in that medium. Class 11 Physics gives a solid foundation for future engineering and medical science courses.
Many new topics, such as Doppler effects, wave types, and their interrelationships, have been introduced in NCERT solutions for Class 11 Physics Chapter 15. Students in class 11 must get in-depth knowledge and conceptual clarity of various topics in this subject in order to perform better on exams and in competitive tests.
Students will learn about the increasing importance of waves in both mediums thanks to Extramarks NCERT solutions.
Our team of subject matter experts have created NCERT Solutions for Class 11 Physics Chapter 15 Waves with the goal of assisting students in their term – II exams. Students can obtain additional information about the chapter and have a short refresher before their second term test by practicing questions from the NCERT textbook using the
Solutions. NCERT Solutions for Class 11 Physics Chapter 15, have been in accordance with the latest CBSE Syllabus 2022-23, to give a solid foundation of fundamental topics that will aid students in their higher studies.
NCERT Solutions for Class 11 Physics Chapter 15 – Waves
NCERT Solutions for Class 11 Physics Chapter 15 include answers to extra questions created by Extramarks specialists, as well as exemplary problems, worksheets, short and long answer questions, MCQs, and tips and techniques for CBSE exam preparation with NCERT Solutions.
This chapter contains different types of questions and responses on important topics in physics, such as questions on wave dynamics and so on. This chapter’s questions are frequently used in second-term exams and will lead you through each and every topic and form of waves, including stress on strings, sound speed in air, transverse wave, and the influence of sound speed in air on parameters such as pressure, humidity, and temperature. This chapter also includes questions on ultrasonic sound wavelengths, transverse harmonic waves, and their applications.
NCERT Solutions for Class 11 Physics Chapter 15
NCERT Class 11 Physics Chapter 15 solutions cover all of the important subjects and subtopics with detailed explanations to help students in class 11 better understand the concepts.
Students will find many practice problems as well as a full explanation of the chapter’s questions and solutions in the Waves Class 11 NCERT solutions.
The foundation for class 12 CBSE boards, which defines the basis to gain admittance into higher educational institutes, is laid by Physics, Chemistry & Mathematics . This chapter in particular lays emphasis on concepts and theoretical components which is important for the Class 12 CBSE board examination point of view. It was created using the latest CBSE syllabus followed by NCERT books which are crucial for CBSE board students .
Physics is a science that involves a lot of numbers, formulae, and graphs. Before the final exam, students frequently seek quick references. The PDF includes a variety of practice questions, including short- and long-answer type questions, multiple-choice questions, diagrammatic and graphic representations..
Before the class 11 final exams, students can quickly review and revise various formulas and numerical valuations without feeling anxious or stressed.
NCERT Solutions : An overview of Physics Chapter 15
We used a wire as a reference for signifying a wave motion in the NCERT Solutions for Class 11 Physics, and we learn about the transverse displacement of a wire that is clamped on both sides, and how to find out the amplitude of a point at a specific distance in the wire. We also had queries about determining the speed of sound in a wire with pistons at one end and a tuning fork at the other. During competitive tests, these topics are quite significant. Waves is also one of the most significant topics in Physics, and students frequently get questions based on them in various competitive exams. NCERT Solutions for Class 11 Physics can help you to crack these exams with ease since all these tricky questions have been covered in practice tests, sample papers and the like.
Solving questions about the speed of sound in a steel medium can teach us a lot about waves. There are concerns about how your guitar strings make sound and the frequency of each string on a guitar. We now understand why the pressure antinode of a sound wave is also a displacement node and vice versa. We’ll also learn how a blind dolphin navigates around obstacles in a river and seeks prey. If a man stands at a specific distance from an observer and blows a horn, we can determine the frequency of the horn-based on whether the man is running towards or away from the observer.
A similar example can be of a truck blowing the horn at a man at a petrol pump, how to find its frequency, speed and wavelength.
Some of the characteristics of waves include: frequency, amplitude, wavelength, phase, resonance, and displacement of waves such as longitudinal and transverse motion in diverse mediums.
The Waves Chapter of Class 11 includes a wide range of topics, including:
- The nature of waves in various mediums
- Waves and their qualities are represented graphically
- Wave by wave comparison
- Sound velocity
- A symphony of motion
- Calculation and resonance between waves
- Oscillation displacement and velocity
Subtopics of Class 11 Physics Chapter 15 Waves
- Transverse and longitudinal waves
- Displacement relation in a progressive wave
- The speed of a travelling wave
- The principle of superposition of waves
- Reflection of waves
- Doppler effect
Rotating electrons, protons, neutrons, and other elementary particles are linked to waves. Molecules and atoms are also related to waves.
To assist students, Extramarks gives chapter-by-chapter NCERT Solutions for all classes. For students to learn more efficiently, all of the solutions in this study material are explained in simple language and in an interactive format.
These NCERT Solutions for Class 11 Physics, Chapter 15, Waves, cover all aspects of the topic, including definitions and examples. These NCERT Solutions are available free of cost.. Students must access NCERT Solutions to take maximum advantage by visiting Extramarks website for guided practice and brilliant performance this year and the year ahead.
Benefits of NCERT Solutions for Class 11 Physics Chapter 15
Following are the benefits of NCERT Solutions:
- Students will be able to approach their revision with more clarity and less fear, doubt or anxiousness for the final Class 11 exam. Students can ace such exams more confidently with the help of the NCERT Solutions. .
- Students can access NCERT Solutions to put themselves in a better position for competitive exams. The majority of students take JEE Main,JEE Advanced and medical exams. Additionally, the content from Solutions can be of great help in their preparation.
- Extramarks website offers free NCERT solutions for Class 11 Physics..
- The NCERT Solutions for Class 11 Physics Chapter 15 Waves were created by a team of teachers with years of experience teaching science and engineering students across the country and abroad.
- Students can easily access NCERT Solutions for Class 11 Physics Chapter 15 from anywhere. It saves time and is tailor-made for easy comprehension and thorough preparation.
It’s an important chapter in Physics. An overtone is a sound frequency that is higher than the fundamental frequency. The term “overtone” is applied to higher-frequency standing waves.
It is a frequency that is typically generated by instruments. Second harmonic is another name for overtone. One of the key advantages of overtone is that it can adapt to any fundamental frequency valuation.
Q.1 A string of mass 2.50 kg is under a tension of 200 N. The length of the stretched string is 20.0 m. If the transverse jerk is struck at one end of the string, how long does the disturbance take to reach the other end?
Q.2 A stone dropped from the top of a tower of height 300 m high splashes into the water of a pond near the base of the tower. When is the splash heard at the top given that the speed of sound in air is 340 m s–1? (g = 9.8 m s–2)
Q.3 A steel wire has a length of 12.0 m and a mass of 2.10 kg. What should be the tension in the wire so that speed of a transverse wave on the wire equals the speed of sound in dry air at 20°C = 343 ms–1.
No, the converse of the given statement is not true. The essential requirement for a function to represent a travelling wave is that it should remain finite for all values of x and t. Out of the given functions, only function (c) satisfies this condition, the remaining functions cannot represent a travelling wave.
Q.6 A bat emits ultrasonic sound of frequency 1000 kHz in air. If the sound meets a water surface, what is the wavelength of (a) the reflected sound, (b) the transmitted sound? Speed of sound in air is 340 m s–1 and in water 1486 m s–1.
Q.7 A hospital uses an ultrasonic scanner to locate tumours in a tissue. What is the wavelength of sound in the tissue in which the speed of sound is 1.7 km s–1? The operating frequency of the scanner is 4.2 MHz.
Q.9 For the wave described in Exercise 15.8, plot the displacement (y) versus (t) graphs for x = 0, 2 and 4 cm. What are the shapes of these graphs?
In which aspects does the oscillatory motion in travelling wave differ from one point to another: amplitude, frequency or phase?
Q.10 For the travelling harmonic wave
y (x, t) = 2.0 cos 2p (10t – 0.0080x + 0.35)
Where x and y are in cm and t in s. Calculate the phase difference between oscillatory motion of two points separated by a distance of
(a) 4 m,
(b) 0.5 m,
Q.11 The transverse displacement of a string (clamped at its both ends) is given by
Where x and y are in m and t in s. The length of the string is 1.5 m and its mass is 3.0 ×10–2 kg.
Answer the following:
(a) Does the function represent a travelling wave or a stationary wave?
(b) Interpret the wave as a superposition of two waves travelling in opposite directions. What are the wavelength, frequency, and speed of each wave?
(c) Determine the tension in the string.
Q.12 (i) For the wave on a string described in Exercise 15.11, do all the points on the string oscillate with the same
(c) amplitude? Explain your answers.
(ii) What is the amplitude of a point 0.375 m away from one end?
Q.13 Given below are some functions of x and t to represent the displacement (transverse or longitudinal) of an elastic wave. State which of these represent (i) a traveling wave, (ii) a stationary wave or (iii) none at all:
(a) y = 2 cos (3x) sin (10t)
(c) y = 3 sin (5x – 0.5t) + 4 cos (5x – 0.5t)
(d) y = cos x sin t + cos 2x sin 2t
(a) The given relation represents a stationary wave. This is due to the fact that the harmonic terms kx and ωt appear separately in the equation.
(b) Since the given equation does not contain any harmonic term, therefore, it cannot represent travelling or stationary wave.
(c) The given equation represents a travelling wave. This is because the harmonic terms kx and ωt are in the form of of kx – ωt in the equation.
(d) The given equation represents the sum of two functions each of which represents a stationary wave. This is because the harmonic terms kx and ωt appear separately in the equation. Therefore, the given equation represents the superposition of two stationary waves.
Q.14 A wire stretched between two rigid supports vibrates in its fundamental mode with a frequency of 45 Hz. The mass of the wire is 3.5 × 10–2 kg and its linear mass density is 4.0 × 10–2 kg m–1. What is (a) the speed of a transverse wave on the string, and (b) the tension in the string?
Q.15 A metre-long tube open at one end, with a movable piston at the other end, shows resonance with a fixed frequency source (a tuning fork of frequency 340 Hz) when the tube length is 25.5 cm or 79.3 cm. Estimate the speed of sound in air at the temperature of the experiment. The edge effects may be neglected.
Q.16 A steel rod 100 cm long is clamped at its middle. The fundamental frequency of longitudinal vibrations of the rod is given to be 2.53 kHz. What is the speed of sound in steel?
Q.17 A pipe 20 cm long is closed at one end. Which harmonic mode of the pipe is resonantly excited by a 430 Hz source? Will the same source be in resonance with the pipe if both ends are open? (Speed of sound in air is 340 m s–1).
Q.18 Two sitar strings A and B playing the note ‘Ga’ are slightly out of tune and produce beats of frequency 6 Hz. The tension in the string A is slightly reduced and the beat frequency is found to reduce to 3 Hz. If the original frequency of A is 324 Hz, what is the frequency of B?
Q.19 Explain why (or how):
(a) In a sound wave, a displacement node is a pressure antinode and vice versa,
(b) Bats can ascertain distances, directions, nature, and sizes of the obstacles without any “eyes”,
(c) A violin note and sitar note may have the same frequency, yet we can distinguish between the two notes,
(d) Solids can support both longitudinal and transverse waves, but only longitudinal waves can propagate in gases, and
(e) The shape of a pulse gets distorted during propagation in a dispersive medium.
(a) Node is a point where the amplitude of oscillation is the minimum and pressure is the maximum. On the contrary, antinode is a point where the amplitude of oscillation is the maximum and pressure is the minimum.
Therefore, in a sound wave, a displacement node is a pressure antinode and vice versa.
(b) Bats emit ultrasonic sound waves of very high-frequency. When these waves are reflected by obstacles in their path, the bat receives a reflected wave and estimates the nature, direction, distance and size of an obstacle.
(c) Although a violin note and a sitar note have the same frequency, but the overtones and their strengthsare different. Thus, we can differentiate the notes produced by a sitar and a violin even if they have the same frequency of vibration.
(d) Solids have both elasticity of shape and elasticity of volume (shear modulus) . Longitudinal waves require the elasticity of shape in the medium for their propagation. Transverse waves propagate in the medium with elasticity of volume. Thus, the solids can support both longitudinal and transverse wave whereas, gases have only the volume elasticity, therefore, the transverse waves cannot propagate through gases.
(e) A sound pulse is a combination of waves having different wavelengths. The shape of wave pulse gets distorted due to propogation of waves in a dispersive medium with different velocities.
Q.20 A train, standing at the outer signal of a railway station blows a whistle of frequency 400 Hz in still air.
(i) What is the frequency of the whistle for a platform observer when the train
(a) approaches the platform with a speed of 10 ms–1,
(b) recedes from the platform with a speed of 10 ms–1?
(ii) What is the speed of sound in each case? The speed of sound in still air can be taken as 340 m s–1.
Q.21 A train, standing in a station-yard, blows a whistle of frequency 400 Hz in still air. The wind starts blowing in the direction from the yard to the station with at a speed of 10 m s–1. What are the frequency, wavelength, and speed of sound for an observer standing on the station’s platform? Is the situation exactly identical to the case when the air is still and the observer runs towards the yard at a speed of 10 ms–1? The speed of sound in still air can be taken as 340 m s–1.
Q.23 A narrow sound pulse (for example, a short pip by a whistle) is sent across a medium.
(a) Does the pulse have a definite (i) frequency, (ii) wavelength, (iii) speed of propagation?
(b) If the pulse rate is 1 after every 20 s, (that is the whistle is blown for a split of second after every 20 s), is the frequency of the note produced by the whistle equal to 1/20 or 0.05 Hz?
(a) A narrow sound pulse has neither a definite wavelength nor a definite frequency. However, its speed remains the same, which is equal to the speed of sound in that medium.
(b) If the pulse rate is 1 after every 20 seconds, it does not mean that the frequency of note produced by the whistle is 0.05 Hz. Rather, it implies that, 0.05 Hz is the frequency of the repetition of the short pip of the whistle.
Q.24 One end of a long string of linear mass density 8.0 × 10–3 kg m–1 is connected to an electrically driven tuning fork of frequency 256 Hz. The other end passes over a pulley and is tied to a pan containing a mass of 90 kg. The pulley end absorbs all the incoming energy so that reflected waves at this end have negligible amplitude. At t =0, the left end (fork end) of the string x = 0 has zero transverse displacement (y =0) and is moving along positive y-direction. The amplitude of the wave is 5.0 cm.
Write down the transverse displacement y as function of x and t that describes the wave on the string.
Q.25 A SONAR system fixed in a submarine operates at a frequency 40.0 kHz. An enemy submarine moves towards the SONAR with a speed of 360 km h–1. What is the frequency of sound reflected by the submarine? Take the speed of sound in water to be 1450 m s–1.
Q.26 Earthquakes generate sound waves inside the earth. Unlike a gas, the earth can experience both transverse (S) and longitudinal (P) sound waves. Typically the speed of S wave is about 4.0 km s–1, and that of P wave is 8.0 km s–1. A seismograph records P and S waves from an earthquake. The first P wave arrives 4 min before the first S wave. Assuming the waves travel in straight line, at what distance does the earthquake occur?
Q.27 A bat is flitting about in a cave, navigating via ultrasonic beeps. Assume that the sound emission frequency of the bat is 40 kHz. During one fast swoop directly toward a flat wall surface, the bat is moving at 0.03 times the speed of sound in air. What frequency does the bat hear reflected off the wall?
FAQs (Frequently Asked Questions)
1. Why should I refer to the NCERT Solutions for Class 11 Physics Chapter 15 Waves?
The new topics addressed in this chapter are tough for students of Class 11. During class hours, students can clarify their doubts from teachers or by accessing reference material available online. . As a result, selecting the appropriate study material necessitates a thorough comprehension of the present CBSE Syllabus 2022-23. All of the chapters in the prescribed textbook are covered in the NCERT Solutions for Class 11 Physics Chapter 15 Waves.
2. How to score more marks in Chapter 15 of NCERT Solutions for Class 11 Physics?
The NCERT Solutions for Class 11 Physics Chapter 15 equip students with a solid foundation of fundamental ideas. The experts at Extramarks provide accurate solutions based on the latest term – II CBSE marks weightage. Students will obtain a better understanding of the concepts that are crucial for the term – II exams by consulting and preparing thoroughly with solutions. Students can retain concepts more successfully with the help of quality answers, a structured approach and guided practice and doubt-clearing sessions.
3. How to differentiate the transverse and longitudinal waves in Chapter 15 of NCERT Solutions for Class 11 Physics?
The main concept presented in Chapter 15 is waves and their qualities. Students can discern longitudinal and transverse as a result of this, based on the problems in the NCERT textbook. Students can also gain a good knowledge and understanding of the concepts that are necessary for the second term exam by regularly using the NCERT Solutions by Extramarks.
4. What are the necessary tips to follow while studying NCERT Class 11 Physics Chapter 15?
Students can follow the tips given below:
- The NCERT Solutions by Extramarks can be used by students for reference when answering textbook questions.
- The answers will assist you in comprehending the logic behind the questions and how to answer them correctly..
- These can be used by students when they get stuck on a question.
- These solutions will also be useful to students studying for competitive exams as well.
- NCERT solutions would be an excellent tailor-made study resource for students to improve their scores and boost their confidence levels as well.
5. What are the factors that influence the velocity of sound?
Some of the factors affecting the velocity of sound are:
- The square root of the density of the particular gas is always inversely proportional to the velocity of the gas.
- In a gas, the square of the absolute temperature of sound is always directly proportional to its velocity.
- Changes in gas pressure have no effect as long as the temperature remains constant.
- When comparing dry and moist air, the speed of sound velocity is greater in moist air because the density of moist air is less than that of dry air.
6. What are the fundamental properties of waves?
There are different fundamental properties in every wave. Reflection, refraction, diffraction, and interference are the four basic properties of waves. Wavelength, frequency, amplitude, and speed are all components of waves. A wave is defined by its amplitude, length, and frequency.
7. Is Class 11 Physics Chapter 15 difficult?
No, Chapter 15 of Physics for Class 11 is not difficult. However, good preparation is essential to perform well on the exam. To take advantage of this, the student must thoroughly study all the chapters and highlight all of the key points so that they may be referred to quickly when needed. They should also develop the practice of taking their own notes so that they can remember the concepts and ideas presented in the chapter. Finally, it goes without saying that students should obtain NCERT solutions and practise sample papers, and model question papers shared with students on a regular basis. Undoubtedly students will be able to get good marks now and perform well in other competitive exams later.