Making waves

MAKING WAVES


Defintion of Waves: A disturbance or variation that transfers energy progressively from point to point in a medium and that may take the form of an elastic deformation or of a variation of pressure, electric or magnetic intensity, electric potential, or temperature.


Waves are catogrised in two different groups


Mechanic or Electromagnetic


Mechanical Waves:the energy is transferred by vibrations of medium (medium = matter)


  • They are split in two types of wave forms which are Transverse and Longitudinal


Transverse: The motion in which all points on a wave oscillate along paths at right angles to the direction of the wave's advance.

Examples of transverse waves

  • Water ripples

  • rope

  • Light

  • Earthquake


Longitudinal: a type of wave in which the medium's vibration is parallel to the direction of the wave, and the medium's displacement is in the same direction as that of the wave movement. Such as sound waves vibrating surface in contact with air.

Examples:

  • Sound

  • Slinky


Properties of Tranverse Waves


  • The wavelength of a wave is the distance from one point of the wave to the next identical point of the wave.(Measured in cm or m)

  • The period of a wave is the time it takes one wave to pass a point

  • The frequency of a wave is the number of wavelengths that pass a point each second.
    The energy carried by a wave depends on its frequency and amplitude. The higher the frequency the larger amplitude, the more energy the wave carries.

  • The amplitude of a wave is the distance from the zero displacement position of the matter particles to a maximum displacement position (a cres or trough). Measured in cm or m.

  • The zero displacement position indicates where the particles would be if npo energy was being transferred through the medium.

  • A crest is the position of maximum upward displacement of a particle-the “top of the wave”

  • A trough is a position of maximum downward displacement of a particle- the “bottom of the wave


Properties of Longitudinal Waves

  • The wavelength of a wave is the distance from one point of the wave to the next identical point of the wave.(Measured in cm or m)

  • The period of a wave is the time it takes one wave to pass a point

  • The frequency of a wave is the number of wavelengths that pass a point each second.
    The energy carried by a wave depends on its frequency and amplitude. The higher the frequency the larger amplitude, the more energy the wave carries.

  • The amplitude of a wave is the distance from the zero displacement position of the matter particles to a maximum displacement position . Measured in cm or m.

  • The zero displacement position indicates where the particles would be if no energy was being transferred through the medium

  • Both rarefactions and compressions are positions of zero displacement in a longitudinal wave.

  • In a longitudinal wave, the direction ofthe movement of particles in matter is back and forth along the direction of the transfer energy.



How to Calculate Waves


Velocity=Speed
Frequency:Hertz (Hz)
Wavelength: Distance (cm or m)



Electromagnetic Waves


Electromagnetic Specturm:

KEY POINTS ON ELECTROMAGNETIC WAVES

  • All electromagnetic waves travel at the same speed – the speed of light.

  •  The property that makes electromagnetic waves behave differently is their wavelength. This is related to how much energy they transfer from one place to another: the shorter the wavelength, the higher the energy. For example, X-rays have very short wavelengths and very higher energy. In contrast, radio waves have long wavelengths and low energy.


Uses of Electromagnetic radiation


  • Radio Waves:Television,Phones and Wi-Fi

  • Micro Waves:Microwave Ovens, Radars, Satellite communication

  • Infrared Waves:Remote Controls,Thermal Imaging, Heating

  • Visible light: Human vision, Illumination, photography and videography.

  • Ultraviolet Waves: Sterilization, Tanning, forensics

  • X-rays:Medical Imaging, Security screening

  • Gamma Waves: Astrophysics, Cancer treatment, Nuclear medicine21


LIGHT:


Light is a type of energy. Unlike sound, light can travel through space even where there is no matter.



Reflection of Light:


Light always travels through air at the same speed and in a straight line. When light hits an object, some of it bounces or reflects off the surface. The type of surface determines how the light reflects:


  • Uneven or rough surfaces reflect light rays in different directions. This scattering of light is called diffuse reflection.

  • In contrast, smooth, shiny surfaces reflect light rays in a regular pattern. This allows us to see a clear image reflected back at us and is called regular reflection. Mirrors are a great example of this.

Law of reflection

The way a light ray reflects off a surface follows a simple pattern. The incoming ray is called the incident ray. To work out the direction of the reflected ray, we can think of a line at right angles to the surface. This line is called the normal. As shown in the diagram below:

  • The angle between the incident ray and the normal is called the angle of incidence.

  •  The angle between the reflected ray and the normal is called the angle of reflection.

Lenses

A lens is a curved piece of transparent glass or plastic that refracts light. Since a lens is curved on at least one side, light rays striking different parts of its curved surface change direction by different amounts.

Depending on the shape of the lens the light can either:

  • Get further apart, or diverge

  • Get closer together, or converge

Concave Lenses

 A lens that is curved inwards and is thinner in the middle is called a concave lens.

  • Concave lenses cause parallel light rays to diverge, or spread out. Because the rays diverge in this way they appear to an observer to come from one point. This is called the focal point.

  • The distance from the focal point to the centre of the lens is called the focal length.

Convex Lenses

  • A lens that is curved outwards and is thicker in the middle is called a convex lens.

  • Convex lenses cause parallel light rays to converge, or get closer together. The point where parallel rays converge is called the focal point. Just as for concave lenses, the distance between the focal point and the centre of the lens is the focal length.

  • In CONVECTION, heat energy is carried by the movement of particles of matter.


  •  In CONDUCTION, heat is transferred by particles vibrating.


  • In RADIATION, heat is carried directly by electromagnetic waves. When a hot object touches a cool object, heat moves from the hot one to the cool one.




Waves


Frequency = 1/Time Period

Time period = 1/Frequency

Speed of Wave = Wavelength x Frequency


  • The frequency of a wave is the number of waves that pass by each second, the symbol F is given for Frequency, and is measured in hertz (hz). Hertz measures how many complete cycles per second.


  • Period: The time it takes to happen, the period of a wave is the time for one complete cycle. This would be measured in seconds.

  • Wavelength: The wavelength is the distance between a point on one wave and the same point on the next wave. e.g.

Wavelength is given the symbol ‘LAMBDA’ and is usually measured in meters. 

Wavelengths can vary hugely in size.


  • Amplitude - As waves travel they create disturbance, the amplitude of a wave is the distance from the maximum disturbance to the undisturbed position. e.g.




  • The straight line that runs through the wavelength is called the Equilibrium or the rest position.  





Longitudinal and Transverse


Longitudinal waves: This is where the particles vibrate parallel to the direction in which the wave of energy is traveling.


Transverse waves: transverse wave, motion in which all points on a wave vibrate along paths at right angles to the direction of the waves advance.

Calculating Wavelengths

In this transverse wave there is one full wavelength and one half this would mean the wavelength frequency is 1.5hz


Electromagnetic Spectrum 


Electromagnetic waves are transverse waves.





Light:

Reflection:

The angle of incidence is always the same as the angle of reflection. Reflection is normally regarded with a mirror. Reflection means the throwing back by a body or surface of light, heat or sound without absorbing it.



Dispersion

Dispersion is a phenomenon in which a white ray of light passes through a glass prism which creates VIBGYOR. When all the colors of VIBGYOR combine they create a white light ray.


Refraction:

 

Refraction refers to the bending of a ray when it passes at an angle from one medium to another in which its speed is different. A refraction is normally regarded with glass or even water.