/ Preparation Physics Waves
- What is the Doppler Effect?
- Derivation of Doppler Effect
- Illustrated Examples
- FAQs on Doppler Effect Derivation
What is the Doppler Effect?
The Doppler Effect is the relationship between the frequency change in a wave and the observer relative to the wave source. This phenomenon was named after the physicist Christian Doppler in 1842. The most common example of the Doppler Effect is the sound of a car horn receding in the distance when it reaches the observer. The received frequency of the wave is comparatively higher than the emitted frequency.
The Doppler Effect depends upon various factors, including the observer’s motion, the wave source’s motion, hindrance in the air, the motion of the medium, etc. These effects of the waves are studied separately to know the phenomenon of the Doppler Effect.
Derivation of Doppler Effect
The derivation can be broken down into two main parts,
- When the source is moving.
- When the observer is moving.
To understand both of these effects, let us study in detail.
(i) When the source is moving
Let us understand the effect when the source is moving, and the observer stays in a stationary motion. We assume that the medium is also at rest. Shown below is the illustration of the Doppler Effect when the source is moving:
The formula can be derived as:
(ii) When the observer is moving
In this case, the observer is in motion, and the source remains at rest, now the derivation happens in the opposite manner and records in the observer’s reference frame. Following the same procedure, we can calculate the first- time travel, as follows:
(iii) When both observer and source are moving
There is also a third possibility when both observer and source can be seen moving, the sound wave emits and reaches the observer. The diagrammatic presentation of the same is as follows:
Weightage in Class 11
The chapter ‘Waves’ for class 11 holds a weightage of 5 marks. It consists of 2 short questions of 2 marks and 3 marks each.
Illustrated Examples
1. Provide a diagram example of the Doppler effect when both source and the observer are moving.
Answer:
2. Provide a diagram example showing the Doppler effect when the source is moving.
Answer:
3. State one use of Doppler effect in the medical industry.
Answer: Doppler effect is used to diagnose heart problems.
Image courtesy: NCERT
FAQs on Doppler Effect Derivation
Q: What’s the origin behind the name Doppler Effect?
Q: Explain a basic example of the Doppler Effect.
A: The most common example of the Doppler Effect is the sound of a car horn recedes in the distance when it reaches the observer. The received frequency of the wave is comparatively higher than the emitted frequency.
Q: What factors does the Doppler Effect rely upon?
A: The Doppler Effect depends upon various factors, such as the observer’s motion, the motion of the wave source, hindrance in the air, the motion of the medium, etc.
Q: Explain the two derivative parts of the Doppler Effect?
A:
1) When the source is moving.
2) When the observer is moving.
Q: Name one routine activity during which we can observe the Doppler Effect?
Physics Waves Exam
Student Forum
Anything you would want to ask experts?Answered 2 months ago
Doppler Effect in class 11 chapter 14 waves refers to the variation in the wavelength or frequency of a wave in relation to an observer moving relative to the wave source. When the wave source moves toward the observer, the frequency increases, and waves are compressed. If the source moves away, the
P
Contributor-Level 9
Answered 2 months ago
The speed of a wave can be found by the medium properties through which it travels. For mechanical waves, the speed of the wave depends on the inertia and elasticity of the medium. For example, the speed of a wave is dependent on the mass of the wave per unit length and the tension in the string.
Al
P
Contributor-Level 9
Answered 2 months ago
According to the principle of superposition, when two or more waves overlap in space, due to each individual wave, at any point the displacement is the vector sum of the displacements. The principle of superposition also explains phenomena like interference where waves combine to amplify or cancel o
P
Contributor-Level 9
Answered 2 months ago
A disturbance that travels through the space or medium transferring energy without the net movement of particles is called a wave. Rather than moving along with the wave, the particles of the medium only oscillate about their mean position in a wave motion. The wave is fundamentally different as com
P
Contributor-Level 9
Answered 2 months ago
Shiksha provides Solutions for NCERT Textbooks in well explained and rich conceptual base manner. Students can access NCERT Solutions for Class 11 Physics Chapter 14 Waves, Which offer several benefits to students:
Comprehensive Coverage: The solutions thoroughly address all topics within the chapte
A
Beginner-Level 5
Answered 2 months ago
Class 11 Physics Waves is important for competitive exams like NEET and JEE, though it has moderate weightage. Students can check the weightage below;
- In NEET, it usually covers about 2–3% of the Physics section, with 1–2 questions that are mostly theory-based, like the Doppler effect or wave speed.
- I
C
Beginner-Level 5
Answered 2 months ago
Class 11 Physics Chapter 14 Waves is very important for CBSE exams because it builds the foundation for many topics like frequency, wavelength, wave propogation, amplitude, wave equations. Chapter 14 Waves covers the types of waves, how they move, and important concepts like the superposition princi
J
Beginner-Level 5
Other Class 11th Physics Chapters
- Physics Mechanical Properties of Solids
- NCERT Class 11 Physics
- NCERT Class 11 Notes
- NCERT Notes
- Physics Motion in Plane
- Physics Mechanical Properties of Fluids
- Physics Motion in Straight Line
- Physics System of Particles and Rotational Motion
- Physics Oscillations
- Physics Waves
- Physics Thermal Properties of Matter
- Physics Motion
- Physics Gravitation
- Physics Thermodynamics
- Physics Work, Energy and Power
- Physics Units and Measurement
- Physics Laws of Motion
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What is the Doppler Effect and how does it relate to waves?