CBSE Class 11 Physics Revision Notes Chapter 15

Class 11 Physics Revision Notes for Chapter 15 – Waves

Waves and Vibrations are fundamentally important phenomena. In this nature, oscillations can be found in a wide variety of forms. Students can easily find examples of vibrations in almost every physical system, from the large oscillations of sea waves to the atomic jiggling. In terms of Physics, a wave is an oscillation or a disturbance that moves through space and time while undergoing an energy transfer. When energy is transferred between two points by wave motion, the medium’s particles are frequently not permanently moved, so there is little or no associated mass transport. Instead, they consist of vibrations or oscillations near fixed points. 

To understand these concepts, students can refer to Extramarks Class 11 Physics Chapter 15 Notes. These notes are easily accessible and will help them study well for the upcoming exams.

Class 11 Physics Revision Notes for Chapter 15 – Waves – Free Download

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Physics Class 11 Revision Notes for Chapter 15- Waves

A common misunderstanding about waves is cleared in this chapter. While waves do not transfer mass, they do transfer energy. Take a few yards out to sea floating ball as an example to quickly understand this. The ball in the example will not come closer to the shore due to wave propagation or the movement of waves toward the shore.

Although the ball won’t be transported by the waves, other elements like winds, tides, or currents may finally help it get to land. Only waves that are perpendicular to the wave’s direction of propagation and move up and down can affect masses.

Depending on the direction of oscillation, a wave can be either transverse or longitudinal. When oscillations parallel to the propagation of the disturbance cause a disturbance, transverse waves can also be created. When oscillations are parallel to the propagation direction, longitudinal waves are created. While all mechanical waves are longitudinal, all electromagnetic waves are transverse. An example of longitudinal waves is sound.

Waveforms

The formula for F or shape, which is represented by the argument denoted as x vt, was developed by the renowned scientist and physicist D’Alembert. In this argument, it’s easy to state that Constant values correspond to constant values of F, and if x increases then the rate that vt increases here the constant of values occurs. This can be explained as the F function moving in the positive direction of x at velocity v and G moving in the negative direction of x at the same speed. 

The periodicity of F in space has the meaning that a snapshot of the wave at a given time denoted as t finds the wave varying periodically in space with the period denoted as the wavelength of the wave. This is another instance of a periodic function F with period denoted as, that is, F(x + λ − vt) = F(x − vt). This periodicity of F also implies a periodicity in time t, as shown by the equation F(x − v(t + T)) = F(x − vt) then vT =, allowing us to observe the wave at a fixed location, x, where we find the wave periodically undulating in time with period T = /v.

Phase Velocity and Group Velocity

When a red square is taken into consideration, it moves with the phase velocity while the green circles, which we take to be another mark, move with the group velocity.

The group velocity and the phase velocity are the two velocities connected to waves.

The definition of velocity that is the same phase is the rate at which the wave’s phase propagates through space at any phase that the wave provides, such as the crest that appears to move at the phase velocity. Lambda is the wavelength used to represent the phase velocity, and T is the time period.

The second component, group velocity, is a property of waves with a defined envelope that measures the wave’s movement through space while taking into account its overall shape, amplitude and envelope.

Types and Features of Waves

The two different forms of waves are longitudinal and transverse waves. Transverse waves resemble those on the water’s surface that are going up and down, whereas longitudinal waves resemble those that are similar to sound waves. The high and low points of a transverse wave are located at its crest and trough respectively. For longitudinal waves, refractions and compressions are equivalent to crests and transverse waves. 

The wavelength is the separation between subsequent troughs and crests. The amplitude of a wave is referred to as its height. The frequency is the number of crests and troughs that pass a particular location in a given amount of time. The wavelength multiplied by the frequency can be used to express the wave velocity.

Even though there is little oscillation at one point, waves can travel great distances. For example, a thunderclap can be heard kilometres from the location where it actually occurred, but the sound carried only causes minute refraction of air and compressions at each location.

Waves exhibit several fundamental phenomena. For example, when a wave encounters an obstruction, it experiences the reflection phenomenon. Refraction is a phenomenon where a wave bends as it enters a medium with a different speed. In the diffraction phenomenon, the waves spread out when they pass through any small openings and bend when they pass around any small obstructions.