When you watch television, listen to the radio or cook something in a microwave oven , you are actually apply the properties of electromagnetic waves. Do you know what is an electromagnetic wave?
Electromagnetic waves are propagating waves that travel in space with both electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation.
Electromagnetic waves carry energy and momentum which may be given when they interact with matter.
Electromagnetic waves comprise of a series of waves whose frequencies and wavelengths extend over a broad range. Waves in the electromagnetic spectrum vary in size from very long radio waves to very short gamma rays.
Visible light waves are the only electromagnetic waves we can see. We see these waves as the colours of the rainbow. Each colour has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they produce white light.
When white light shines through a prism or through water vapour, the white light is broken apart into the colours of the visible light spectrum.
The electromagnetic spectrum is the range of frequencies and wavelengths over which electromagnetic waves are propagated.
Sources of Electromagnetic Waves.
Matter is made up of elementary particles called atoms.
Every atom has a nucleus at its centre which is surrounded by orbiting electrons.
Electrons are negatively charged particles and they circle around the nucleus in orbits, each of which is at a specific energy level. When a charged electron travels from an orbit with a particular energy level to one of a lower energy level, electromagnetic waves are emitted.
Electromagnetic waves are also produced when a charged particle (electron or nucleus) oscillates.
Properties of electromagnetic waves
Electromagnetic waves are:
a. Transverse waves
b. Do not require a medium to propagate and can travel in a vacuum.
c. The magnetic and electric field components of the wave oscillate at right angles to each other and to the direction of propagation of the wave.
d. Obey the wave equation c = fλ. c is the velocity of light, f is the frequency of the wave and the λ is the wavelength.
e. In a vacuum , the waves travel at the speed of light c = 3 X 10^8 ms-1.
f. Undergo the same phenomena as light: reflection, refraction, diffraction and interference.
g. The waves are electrically neutral.
h. Show characteristics of polarization.
i. Energy is transferred by the waves.
In a vacuum, c is a constant for all elecgromagnetic waves The formula c = fλ shows that the frequency f is inversely proportional to the wavelength λ. (f = c/λ)
The velocities of an electromagnetic wave in other media are different from its velocity in vacuum.
Detrimental effects of electromagnetic spectrum.
The invisible waves or radiation that are emitted from power lines, cellular phones, radio antenna, could potentially be harmful to our health.
The detrimental effects of excessive exposure of the human body to electromagnetic waves of increasing frequencies:
a. Radio waves: harm body cells, prevalence of migraine, headache disorders.
b. Microwaves: internal heating of body tissue
c. Infrared: skin burns
d. Visible light: increased rates of premature skin aging and skin cancer
e. Ultraviolet: damage to surface cells (including skin cancer) and blindness.
f. X-rays: damage to cells.
g. Gamma rays: cancer, mutation
Showing posts with label Electromagnetic waves. Show all posts
Showing posts with label Electromagnetic waves. Show all posts
2008-07-15
2008-04-06
Analysing Electromagnetic Waves
1. Electromagnetic waves consist of vibration of magnetic field and electric field which are perpendicular to each other.
2. Therefore, Electromagnetic waves are transverse waves.
3. The velocity of electromagnetic waves in vacuum is 3 X 10 (8)(to the power of eight) meter per second.
4. Differences in wavelength between electromagnetic waves producer a spectrum of electromagnetic waves.
Electromagnetic waves sorted starting from High Frequency to the Lowest Frequenct
Gamma rays
X-Rays
Ultraviolet
Visible Light
Infrared
Micro Waves
Radio Waves
Hope you all have an idea :)
2. Therefore, Electromagnetic waves are transverse waves.
3. The velocity of electromagnetic waves in vacuum is 3 X 10 (8)(to the power of eight) meter per second.
4. Differences in wavelength between electromagnetic waves producer a spectrum of electromagnetic waves.
Electromagnetic waves sorted starting from High Frequency to the Lowest Frequenct
Gamma rays
X-Rays
Ultraviolet
Visible Light
Infrared
Micro Waves
Radio Waves
Hope you all have an idea :)
2008-01-11
Understanding Waves
Waves
Understanding Waves
Wave and Energy
A Wave is a disturbance that transfers energy between 2 points through vibrations (or oscillations) in a medium, without transferring matter between the two points.
Example 1: When you hold the end of a rope and a friend of yours wave the rope at the other end up and down, then a wavy movement appears. This is a movement of the rope and it transfers energy but NOT the rope.
Example 2: When you throw a stone on the surface of a calm pond, a circular ripple will appear and subsequently other smaller ripple will appear from the point of origin, these waves will eventually turn into a few big circles which then encompass smaller circular ripples in the middle. What happen is, the kinetic energy from the stone is transferred to the water in the form of ripples, which is an example of wave.
There are two types of waves:
1. Transverse waves
2. Longitudinal waves
Transverse waves
Transverse wave is a wave in which direction of vibration is perpendicular to the direction of movement of wave.
Examples are : water waves, waves on a string, radio waves, light waves and electromagnetic waves.
Longitudinal waves
Longitudinal wave is a wave in which the direction of vibration is parallel to the direction of travel of the wave
Examples are: sound waves and waves on a slinky spring.(which consists of regions of rarefaction and compression).
Wavefronts
Wavefront is a line that joins all the points vibrating in phase, such as a line passing through similar wave crests. It consists of crest and trough. Crest is the peaky part of the wave and trough is the lowest part of the wave.
Wavefront is perpendicular to the direction of wave movement.
Oscillating System:
Waves are produced by oscillating systems (or vibrations) in a medium.
An oscillation is a to and fro movement along a fixed path.
Examples are: Swinging pendulum(horizontally) and a Spring swinging up and down (vertically).
What u must now is that:
One complete oscillation is a to and fro movement of a body when it has returned to its original position and is moving in the same original direction.
Amplitude, a, is the maximum displacement from the resting position.
Period, T, is the time taken to make one complete oscillation.
Frequency, f, is the number of oscillations produced in one second.
Understanding Waves
Wave and Energy
A Wave is a disturbance that transfers energy between 2 points through vibrations (or oscillations) in a medium, without transferring matter between the two points.
Example 1: When you hold the end of a rope and a friend of yours wave the rope at the other end up and down, then a wavy movement appears. This is a movement of the rope and it transfers energy but NOT the rope.
Example 2: When you throw a stone on the surface of a calm pond, a circular ripple will appear and subsequently other smaller ripple will appear from the point of origin, these waves will eventually turn into a few big circles which then encompass smaller circular ripples in the middle. What happen is, the kinetic energy from the stone is transferred to the water in the form of ripples, which is an example of wave.
There are two types of waves:
1. Transverse waves
2. Longitudinal waves
Transverse waves
Transverse wave is a wave in which direction of vibration is perpendicular to the direction of movement of wave.
Examples are : water waves, waves on a string, radio waves, light waves and electromagnetic waves.
Longitudinal waves
Longitudinal wave is a wave in which the direction of vibration is parallel to the direction of travel of the wave
Examples are: sound waves and waves on a slinky spring.(which consists of regions of rarefaction and compression).
Wavefronts
Wavefront is a line that joins all the points vibrating in phase, such as a line passing through similar wave crests. It consists of crest and trough. Crest is the peaky part of the wave and trough is the lowest part of the wave.
Wavefront is perpendicular to the direction of wave movement.
Oscillating System:
Waves are produced by oscillating systems (or vibrations) in a medium.
An oscillation is a to and fro movement along a fixed path.
Examples are: Swinging pendulum(horizontally) and a Spring swinging up and down (vertically).
What u must now is that:
One complete oscillation is a to and fro movement of a body when it has returned to its original position and is moving in the same original direction.
Amplitude, a, is the maximum displacement from the resting position.
Period, T, is the time taken to make one complete oscillation.
Frequency, f, is the number of oscillations produced in one second.
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