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Flashcards in 3. Waves Deck (43)
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What is speed of wave

Distance travelled by a wave peak or trough every second
Unit m/s


What is wavefront

The peak of a transverse wave
The compression of a longitudinal wave


What is frequency

The number of complete waves passing a point in one second
Unit hertz


What is wavelength

Distance from 1 wave peak to another


What is amplitude

The distance from the middle to the peak or the trough
The bigger the amplitude, the more energy it carries


How to calculate speed of wave

Wavelength x frequency
Unit m/s


Describe transverse wave

Vibrations are perpendicular to the direction in which the waves are traveling


Describe longitudinal waves

Vibrations are parallel to the direction in which the waves are traveling


Describe refraction when waves slow down

When water waves pass through shallow water
Wavefront crowded together so wavelength gets smaller
Waves slow down when pass from a less to a more dense material
When a wave is slowed down, it is refracted toward the normal


Describe refraction when a wave speed up

Wavefront spread out -> wavelengths gets larger
Move from a denser to a less dense material
It is refracted away from the normal


Describe diffraction

It is the spreading of waves when they pass through a gap or move past an obstacle
Narrower the gap, the more waves spread out and vice versa
Wavelength does not change on diffraction
For noticeable diffraction, the gap must be similar size to wavelength


Describe the image given by reflection

As far behind the mirror as the object is in the front
Same size as object
Laterally inverted ( left and right are swap around)
The image is virtual, cannot be focused on a screen


What is the law of reflection

Angle of incidence = angle of reflection


Describe the angle of refraction and incidence when light refract

Travel from less dense -> more dense
I > r
Travel from a more dense -> less dense
R> I


What is critical angle

The angle at which the refracted ray emerges along the boundary


What happen if i > or

I > critical angle -> the light ray is totally internally reflected
I refraction


How to calculate the refractive index

Speed of light in air / speed of light in medium
Sin I / sin r


Define refractive index

A measure of the change of direction of a light ray at non-normal incidence when it passes from air into the substance


What is the law of refraction

Refractive index = sin I / sin R


What is the principal focus

The point where parallel Ray directed straight at the converging lens are focused


What is the focal length

The distance from the lens to the principal focus


How does converging lens work

By changing the direction of light passing through it


When is a real and inverted image formed if light is directed through a converging lens

If the object is further from the lens than the principal focus is


When is the image real and diminish

When object is beyond 2F
Image is between F and the lens


When is an object real and same size

The object is at 2F
Image at 2F on the other side


When is an object real and magnified

The object is between F and 2F
The image is beyond 2


What happen if the object is between F and the lens

The image will be virtual upright, magnified and on the same side as the object


Describe the dispersion of light

White light has all the colors of the visible spectrum in it
Each color light is refracted differently bc the speed of light in glass depend on its color
The result is that the beam of white light is split into separated color by the prism


Describe the main feature of the electromagnetic spectrum

Can travel in high speed through a vacuum
Travel at the speed of light 3x10^8
Can transfer energy
They are transverse wave
When a wave hits an object, the energy it carries is transferred to the object as ke


What is monochromatic

Light of a single wavelength and color