 # Quick Answer: What Is Group Velocity In A Waveguide?

## Does anything travel faster than light?

Tachyons are hypothetical particles that travel faster than light.

According to Einstein’s special theory of relativity – and according to experiment so far – in our ‘real’ world, particles can never travel faster than light..

## What velocity means?

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object’s speed and direction of motion (e.g. 60 km/h to the north).

## What is the fastest thing in the world?

And, while light is still by far the fastest thing in the universe, moving at a staggering speed of 299791.82 km/h, the following list contains some of the other closest things to reach that title of “World’s Fastest.”

## What is velocity of wave?

Wave velocity, distance traversed by a periodic, or cyclic, motion per unit time (in any direction). … The velocity of a wave is equal to the product of its wavelength and frequency (number of vibrations per second) and is independent of its intensity.

## What is group velocity in optical fiber?

The group velocity is the velocity with which the envelope of a pulse propagates in a medium, assuming a long pulse with narrow bandwidth (so that higher-order chromatic dispersion is not relevant) and the absence of nonlinear effects (i.e., low enough optical intensities). …

## What is the formula of group velocity?

y = Asin(ωt – kx). On the other hand, group velocity refers to a group composed of waves within a frequency band ∆ω. Group velocity is the velocity with which the entire group of waves would travel. The following figure 1 shows y = sin(2 +t) and y = sin(2 +t) + sin(2 + 1.1t).

## What is difference between group velocity and phase velocity?

The group velocity is the velocity of the wave with lower frequency, but the phase velocity is the velocity of the wave with higher frequency. The resulting wave may be a perturbation that acts over a short distance, i.e. a wave packet. … Phase velocity and group velocity are two very important concepts in physics.

## What is 3dB frequency?

The 3dB point, or 3dB frequency, is the point at which the signal has been attenuated by 3dB (in a bandpass filter). This is generally considered the point for determining the filter’s bandwidth. The bandwidth is defined as the difference between the upper and lower 3dB points.

## What is the purpose of a waveguide?

Waveguides are metal tubes functioning as “conduits” for carrying electromagnetic waves. They are practical only for signals of extremely high frequency, where the signal wavelength approaches the cross-sectional dimensions of the waveguide.

## What is the fastest thing in the universe?

A sequence of radio observations shows a plasma blob moving away from a blazar’s core (right) over about 8.4 months. SAN DIEGO — If you’re light, it’s fairly easy to travel at your own speed — that is to say 186,282 miles per second or 299,800 kilometers per second.

## What is de Broglie’s hypothesis?

De Broglie’s hypothesis of matter waves postulates that any particle of matter that has linear momentum is also a wave. The wavelength of a matter wave associated with a particle is inversely proportional to the magnitude of the particle’s linear momentum. The speed of the matter wave is the speed of the particle.

## What is group velocity and particle velocity?

Waves can be in the group and such groups are called as wave packets, so the velocity with a wave packet travels is called group velocity. Velocity with which the phase of a wave travels is called phase velocity.

## What is the cutoff frequency of a waveguide?

The cutoff frequency of an electromagnetic waveguide is the lowest frequency for which a mode will propagate in it. In fiber optics, it is more common to consider the cutoff wavelength, the maximum wavelength that will propagate in an optical fiber or waveguide.

## Is group velocity always greater than wave velocity?

For surface gravity waves, the water particle velocities are much smaller than the phase velocity, in most cases. Propagation of a wave packet demonstrating a phase velocity greater than the group velocity without dispersion. This shows a wave with the group velocity and phase velocity going in different directions.

## Can group velocity be greater than C?

It is often assumed that relativity restricts the group velocity to be less than the speed of light. … By considering a material in which the tail has the opposite sign, it is shown that the group velocity can be larger than c without having any signal propagate faster than c.

## What does group velocity mean?

noun Physics. the velocity of finite numbers of waves undergoing simple harmonic motion, equal to the phase velocity when it does not vary with the wavelengths of the waves. The group velocity of the set of waves produced in water when a stone is dropped is less than the velocity of the individual waves.

## Can group velocity exceed speed light?

Since the 1980s, various experiments have verified that it is possible for the group velocity (as defined above) of laser light pulses sent through lossy materials, or gainful materials, to significantly exceed the speed of light in vacuum c. The peaks of wavepackets were also seen to move faster than c.

## What is 3 dB cutoff frequency?

The cutoff frequency of a device (microphone, amplifier, loudspeaker) is the frequency at which the output power level is decreased to a value of (−)3 dB below the input power level (0 dB). (−)3 dB corresponds to a factor of ½ = 0.5, which is 50% of the input power (half the value).

## What is phase velocity in transmission lines?

Phase velocity is the propagation velocity of an equiphase wave surface of a single sinusoidal wave along a transmission line, and group velocity is the propagation velocity of the envelope of two sinusoidal waves with a slight difference in frequency superimposed.