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ELECTROMAGNETIC WAVE:
WAVE NATURE OF LIGHT
PROPERTIES OF WAVE
SINE WAVE AND COSINE WAVE
PRESENTED BY
AFSANA ANSARI
B.OPTOMETRY
MMC, IOM
PRESENTATION LAYOUT
Introduction
 WAVE
 PROPERTIES
Theories of nature of light
Electromagnetic wave
Sine wave
Cosine Wave
WAVE
A wave is continuous transfer of disturbance from one part of medium to
another through successive vibrations of particle of medium about their
mean position.
A wave is a disturbance in a medium that carries energy without a net
movement of particles.
 It may take the form of displacement, a variation of pressure, electric or
magnetic field,density.
Electromagnetic wave pptx  by Afsana Ansari
Types of Waves:
The types of waves are given below.
Transverse Waves
Waves in which the particles of medium vibrate about their mean position
perpendicularly to the direction of propagation of wave .
 Crest is point on wave that exhibits maximum positive or upward
displacement from undisturbed position.
 Trough is point on wave that exhibits maximum negative or downward
displacement from undisturbed position.
Examples of transverse waves:
 Light waves
 S-wave earthquake waves
 Stringed instrument
Longitudinal Wave
Wave in which particle of medium vibrate along the direction of
propagation of wave.
Examples of longitudinal waves:
• Sound waves
• P-type earthquake waves
• Compression wave
Compression is the region where particles of medium come closer to
each other.
Rarefaction is the region where particles are farther apart.
Density is greater due to increase in pressure at compression and is less
at rarefaction due to decrease in pressure.
Properties of Waves
The prime properties of waves are as follows:
Amplitude
 Wave is an energy transport phenomenon.
 Amplitude is maximum displacement of medium from its equilibrium
state when mechanical wave passes through medium.
 It is directly related to the amount of energy carried by a wave.
Wavelength
Distance travelled by wave during the time at which any particle of
medium completes one vibration about its mean position.
The distance between identical points in the adjacent cycles of crests of a
wave is called a wavelength.
Period
The period of a wave is the time for a particle on a medium to make one
complete vibrational cycle.
Defined as the time interval which the motion of an oscillating particles
begin to repeat itself.
Denoted by T.
 As the period is time, hence is measured in units of time such as
seconds or minutes.
Frequency
 Frequency of a wave is the number of waves passing a point in a
certain time.
The unit of frequency is hertz (Hz) which is equal to one wave per
second.
The period is the reciprocal of the frequency and vice versa.
Period=1/Frequency
OR
Frequency=1/Period
Speed
 The speed of an object means how fast an object moves and is usually
expressed as the distance travelled per time of travel.
The speed of a wave refers to the distance travelled by a given point on
the wave (crest) in a given interval of time.
Speed=Distance/Time
Speed of a wave is thus measured in metre/second.
Phase
• State of motion of particle at given place and time.
• State of motion of vibrating particle means where is particle and what its
direction of motion.
• Measured in terms of angle called phase angle.
Electromagnetic Waves
These waves are disturbance that does not need any object medium for
propagation and can easily travel through the vacuum.
They are produced due to various magnetic and electric fields.
The periodic changes that take place in magnetic and electric fields and
therefore known as electromagnetic waves. E
M
B
Electromagnetic wave pptx  by Afsana Ansari
• How Are Electromagnetic Waves Formed?
• Generally, an electric field is produced by a charged particle.
• A force is exerted by this electric field on other charged particles.
• Positive charges accelerate in the direction of the field and negative
charges accelerate in a direction opposite to the direction of the field.
• The Magnetic field is produced by a moving charged particle.
• A force is exerted by this magnetic field on other moving particles.
• The force on these charges is always perpendicular to the direction of
their velocity and therefore only changes the direction of the velocity, not
the speed.
• So, the electromagnetic field is produced by an accelerating charged
particle.
• Electromagnetic waves are nothing but electric and magnetic fields
travelling through free space with the speed of light c.
• An accelerating charged particle is when the charged particle oscillates
about an equilibrium position.
• If the frequency of oscillation of the charged particle is f, then it produces
an electromagnetic wave with frequency f.
• The wavelength λ of this wave is given by λ = c/f.
• Electromagnetic waves transfer energy through space
Electromagnetic wave pptx  by Afsana Ansari
THEORIES OF NATURE OF LIGHT
Newton's corpuscular theory
Light consists of tiny particles called corpuscles , shot out by luminous
object such as electric lamp , candle etc
Corpuscles are tiny massless particles shot out at speed of about 3x10
8m/s from lighted object.
Particles travel in st.line and bounce off or pass into an object on striking
it.
On entering the eyes, these corpuscles cause sensation of visionand
various colors due to different sizes of corpuscles.
 Phenomenon of refraction was explained by stating that these corpuscles are
attracted by material of denser medium.
 Speed of light is increased in denser medium and resulted change in direction.
 This theory is based on fact that speed of light must be greater in denser
medium.
 However it was found that light travels slowly in denser medium than in rarer
medium.
 Couldn’t explain interference , diffraction and polarization of light.
Huygen's wave theory
The locus of all medium particles vibrating in the same phase is called a
wave front.
 Each point in a source of light sends out waves in all directions in a
hypothetical medium called ether.
 Ether was assumed to be a continuous medium, which provides all space
having very large elasticity, and extremely low density, which is
homogeneous and isotropic.
This theory assumes that the light waves are mechanical and transverse in
nature.
This theory is successful in explaining the phenomena of reflection,
refraction, interference and diffraction phenomena of light.
 This theory also assumes in similar to the previous theory that the
velocity of light is dependent on the density of the medium but color
depends on the wavelength of the light.
Maxwell's electro magnetic wave theory
The electric and magnetic fields in a electro magnetic wave are
continuously varying with respect to time and space.
 At any instant electric and magnetic fields are perpendicular to each
other and also perpendicular to the direction of light.
 The electro magnetic wave is a transverse wave.
At every point in the wave at a given instant of time the electric and
magnetic field strengths are equal.
The velocity of propagation of electro magnetic wave depends on the
electric and magnetic properties of the medium.
The main drawback of this theory is it failed to explain the photo
electic effect and Compton effect.
 Electro magnetic theory also failed in explaining the black body
radiation
Planck's Quantum theory
 Max plank introduced the concept of quantisation of energy.
 According to this theory, light energy is released from source discretely in the form
of energy packets of specific frequencies called photons or quanta.
 Photons are propagated as waves and if necessary interact with matter as particles.
• Energy(E) = hf
Where;
h - Planck’s Constant (6.626 × 10-34
js)
f – frequency
Therefore, energy increases as frequency increases.
 This phenomena of Compton effect, photoelectric effect and black body
radiation.
 The main drawback of this theory is it could not explain how it is
connected with wave nature of light.
DUAL NATURE OF LIGHT
1. Light Behaves as wave
Light behaves like a particle
Explained by :
ELECTROMAGNETIC SPECTRUM
Electromagnetic wave pptx  by Afsana Ansari
The orderly distribution of electromagnetic radiations according to their
wavelength or frequency is called electromagnetic spectrum.
There are seven types of waves in electromagnetic spectrum.
1. Radiowaves
2. Microwaves
3. Infrared waves
4. Visible waves
5. Ultraviolet waves
6. X-rays
7. γ-rays
Radio waves
Frequency range is from a few Hz to 109
Hz.
Basically used in radio and television communication signals.
Amplitude modulation (AM) band ranges from 530 kHz to 1710 kHz.
Television (TV) waves range from 54 MHz to 890 MHz.
Frequency modulation (FM) radio band extends from 88 MHz to ultrahigh
frequency (UHF) band
Microwaves
• Wavelength ranges from 0.3 m down to 10–3
m.
• The frequency range is from 109
Hz to 3 × 1011
Hz.
• Used to transmit power over long distances.
• Also used in communication satellite transmission. A microwave oven
uses a magnetic microwave generator.
Infra -red Rays
• Produced by hot bodies and molecules, so sometimes called heat waves.
• Infrared lies nearer to the red color of visible spectrum, so it is called infrared.
• Wavelength ranges from 10-3
m to 7.8 × 10–7
m.
• The frequency ranges from 3 × 1011
Hz to 4 × 1014
Hz.
• The infrared wave coming from the sun keeps the earth warm.
• In hospitals, they are used in muscular therapy in physiotherapy
departments.
Visible
• Wavelength ranges from 10-3
m to 7.8 × 10–7
m.
• The frequency ranges from 3 × 1011
Hz to 4 × 1014
Hz.
• Visible light is emitted when electron jump from higher energy level to lower
energy level.
• Useful in photography, optical microscopy , astronomy etc.
Electromagnetic wave pptx  by Afsana Ansari
Ultraviolet Rays
• The wavelength of ultraviolet waves lie nearer to the violet light of visible
spectrum. So, it is named ultraviolet.
• Wavelength ranges from 4 × 10–7
m down to 6 × 10–10
m.
• The frequency ranges from 8 × 1014
Hz to 5 × 1017
Hz.
• They are very harmful to the living tissues so can cause skin cancer.
• These waves are used to preserve food stuffs as the rays kill germs.
X-rays
Produced by bombarding target of high atomic number with beam of fast
moving electrons.
Wavelength ranges from nearly 10–9
m down to 6 × 10–12
m.
The frequency ranges from 3 × 1017
Hz to 5 × 1019
Hz.
Used in medical diagnosis and therapy.
 Are harmful for our body as Biological cells are destroyed, if x-rays are exposed
on them.
Gamma Rays
Produced during radioactive decay of nuclei and nuclear reactions.
 Shortest wavelength ranges from nearly 10–10
m below to 10– 14
m.
 The frequency ranges from 3 × 1018
Hz to 3 × 1022
Hz.
These rays have serious effect on human cells.
 Used to kill the cancerous cells in radiotherapy.
Sine Wave
Sine or sinusoidal wave is the most natural representation of how many
things in nature change state.
A sine wave shows how the amplitude of a variable changes with time.
A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve
defined in terms of the sine trigonometric function.
It is a type of continuous wave and also a smooth periodic function.
The variable could be audible sound.
 Example a single pure note is a sine wave, although it would sound a
very plain and flat note indeed with none of the harmonics we normally
hear in nature.
 A straightforward oscillating or alternating current or voltage within a
wire can also be represented by a sine wave.
The number of times the sine wave goes through a complete cycle in the
space of 1 second is called the frequency.
 Indeed the unit used to be cycles per second, but now the unit of
measurement is hertz (Hz).
 A frequency of 1000Hz, or 1 kHz, means that the sine wave goes through
1000 complete cycles in 1 s.
If we are considering audible sound waves then the human ear has a
frequency range of about 20Hz-20kHz.
• The sine of any angle can vary from 1 to +1.
−
• For example the sine of 0° is 0 and the sine of 90° is 1.
• The sine of 270° is 1 and when we get to 360° we are
−
back to zero again.
• A cosine is 90° out of phase with a sine wave
COSINE WAVE
• The cosine of 0° is 1 and the cosine of 90° is 0.
• So we say that a cosine is 90° out of phase with a sine wave.
• Any number of sine waves can exist at any one time and have any
manner of angular phase differences to each other.
• Whenever a phase angle is mentioned it is always relative to something
else.
• Digital ‘ones’ and ‘zeroes’ can be encoded as two signals of identical
amplitude and frequency but with different phases to each other or some
other reference marker.
• This would be called phase modulation.
REFERENCES
 PICTURES FROM INTERNET
 https://byjus.com/physics/waves/#:~:text=A%20wave%20is%20a
%20disturbance,%2C%20electric%20potential%2C%20or%20temperature

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Electromagnetic wave pptx by Afsana Ansari

  • 1. ELECTROMAGNETIC WAVE: WAVE NATURE OF LIGHT PROPERTIES OF WAVE SINE WAVE AND COSINE WAVE PRESENTED BY AFSANA ANSARI B.OPTOMETRY MMC, IOM
  • 2. PRESENTATION LAYOUT Introduction  WAVE  PROPERTIES Theories of nature of light Electromagnetic wave Sine wave Cosine Wave
  • 3. WAVE A wave is continuous transfer of disturbance from one part of medium to another through successive vibrations of particle of medium about their mean position. A wave is a disturbance in a medium that carries energy without a net movement of particles.  It may take the form of displacement, a variation of pressure, electric or magnetic field,density.
  • 5. Types of Waves: The types of waves are given below. Transverse Waves Waves in which the particles of medium vibrate about their mean position perpendicularly to the direction of propagation of wave .
  • 6.  Crest is point on wave that exhibits maximum positive or upward displacement from undisturbed position.  Trough is point on wave that exhibits maximum negative or downward displacement from undisturbed position. Examples of transverse waves:  Light waves  S-wave earthquake waves  Stringed instrument
  • 7. Longitudinal Wave Wave in which particle of medium vibrate along the direction of propagation of wave. Examples of longitudinal waves: • Sound waves • P-type earthquake waves • Compression wave
  • 8. Compression is the region where particles of medium come closer to each other. Rarefaction is the region where particles are farther apart. Density is greater due to increase in pressure at compression and is less at rarefaction due to decrease in pressure.
  • 9. Properties of Waves The prime properties of waves are as follows: Amplitude  Wave is an energy transport phenomenon.  Amplitude is maximum displacement of medium from its equilibrium state when mechanical wave passes through medium.  It is directly related to the amount of energy carried by a wave.
  • 10. Wavelength Distance travelled by wave during the time at which any particle of medium completes one vibration about its mean position. The distance between identical points in the adjacent cycles of crests of a wave is called a wavelength.
  • 11. Period The period of a wave is the time for a particle on a medium to make one complete vibrational cycle. Defined as the time interval which the motion of an oscillating particles begin to repeat itself. Denoted by T.  As the period is time, hence is measured in units of time such as seconds or minutes.
  • 12. Frequency  Frequency of a wave is the number of waves passing a point in a certain time. The unit of frequency is hertz (Hz) which is equal to one wave per second. The period is the reciprocal of the frequency and vice versa. Period=1/Frequency OR Frequency=1/Period
  • 13. Speed  The speed of an object means how fast an object moves and is usually expressed as the distance travelled per time of travel. The speed of a wave refers to the distance travelled by a given point on the wave (crest) in a given interval of time. Speed=Distance/Time Speed of a wave is thus measured in metre/second.
  • 14. Phase • State of motion of particle at given place and time. • State of motion of vibrating particle means where is particle and what its direction of motion. • Measured in terms of angle called phase angle.
  • 15. Electromagnetic Waves These waves are disturbance that does not need any object medium for propagation and can easily travel through the vacuum. They are produced due to various magnetic and electric fields. The periodic changes that take place in magnetic and electric fields and therefore known as electromagnetic waves. E M B
  • 17. • How Are Electromagnetic Waves Formed? • Generally, an electric field is produced by a charged particle. • A force is exerted by this electric field on other charged particles. • Positive charges accelerate in the direction of the field and negative charges accelerate in a direction opposite to the direction of the field. • The Magnetic field is produced by a moving charged particle. • A force is exerted by this magnetic field on other moving particles. • The force on these charges is always perpendicular to the direction of their velocity and therefore only changes the direction of the velocity, not the speed.
  • 18. • So, the electromagnetic field is produced by an accelerating charged particle. • Electromagnetic waves are nothing but electric and magnetic fields travelling through free space with the speed of light c. • An accelerating charged particle is when the charged particle oscillates about an equilibrium position. • If the frequency of oscillation of the charged particle is f, then it produces an electromagnetic wave with frequency f. • The wavelength λ of this wave is given by λ = c/f. • Electromagnetic waves transfer energy through space
  • 20. THEORIES OF NATURE OF LIGHT Newton's corpuscular theory Light consists of tiny particles called corpuscles , shot out by luminous object such as electric lamp , candle etc Corpuscles are tiny massless particles shot out at speed of about 3x10 8m/s from lighted object. Particles travel in st.line and bounce off or pass into an object on striking it. On entering the eyes, these corpuscles cause sensation of visionand various colors due to different sizes of corpuscles.
  • 21.  Phenomenon of refraction was explained by stating that these corpuscles are attracted by material of denser medium.  Speed of light is increased in denser medium and resulted change in direction.  This theory is based on fact that speed of light must be greater in denser medium.  However it was found that light travels slowly in denser medium than in rarer medium.  Couldn’t explain interference , diffraction and polarization of light.
  • 22. Huygen's wave theory The locus of all medium particles vibrating in the same phase is called a wave front.  Each point in a source of light sends out waves in all directions in a hypothetical medium called ether.  Ether was assumed to be a continuous medium, which provides all space having very large elasticity, and extremely low density, which is homogeneous and isotropic.
  • 23. This theory assumes that the light waves are mechanical and transverse in nature. This theory is successful in explaining the phenomena of reflection, refraction, interference and diffraction phenomena of light.  This theory also assumes in similar to the previous theory that the velocity of light is dependent on the density of the medium but color depends on the wavelength of the light.
  • 24. Maxwell's electro magnetic wave theory The electric and magnetic fields in a electro magnetic wave are continuously varying with respect to time and space.  At any instant electric and magnetic fields are perpendicular to each other and also perpendicular to the direction of light.  The electro magnetic wave is a transverse wave. At every point in the wave at a given instant of time the electric and magnetic field strengths are equal.
  • 25. The velocity of propagation of electro magnetic wave depends on the electric and magnetic properties of the medium. The main drawback of this theory is it failed to explain the photo electic effect and Compton effect.  Electro magnetic theory also failed in explaining the black body radiation
  • 26. Planck's Quantum theory  Max plank introduced the concept of quantisation of energy.  According to this theory, light energy is released from source discretely in the form of energy packets of specific frequencies called photons or quanta.  Photons are propagated as waves and if necessary interact with matter as particles. • Energy(E) = hf Where; h - Planck’s Constant (6.626 × 10-34 js) f – frequency Therefore, energy increases as frequency increases.
  • 27.  This phenomena of Compton effect, photoelectric effect and black body radiation.  The main drawback of this theory is it could not explain how it is connected with wave nature of light.
  • 28. DUAL NATURE OF LIGHT 1. Light Behaves as wave
  • 29. Light behaves like a particle Explained by :
  • 32. The orderly distribution of electromagnetic radiations according to their wavelength or frequency is called electromagnetic spectrum. There are seven types of waves in electromagnetic spectrum. 1. Radiowaves 2. Microwaves 3. Infrared waves 4. Visible waves 5. Ultraviolet waves 6. X-rays 7. γ-rays
  • 33. Radio waves Frequency range is from a few Hz to 109 Hz. Basically used in radio and television communication signals. Amplitude modulation (AM) band ranges from 530 kHz to 1710 kHz. Television (TV) waves range from 54 MHz to 890 MHz. Frequency modulation (FM) radio band extends from 88 MHz to ultrahigh frequency (UHF) band
  • 34. Microwaves • Wavelength ranges from 0.3 m down to 10–3 m. • The frequency range is from 109 Hz to 3 × 1011 Hz. • Used to transmit power over long distances. • Also used in communication satellite transmission. A microwave oven uses a magnetic microwave generator.
  • 35. Infra -red Rays • Produced by hot bodies and molecules, so sometimes called heat waves. • Infrared lies nearer to the red color of visible spectrum, so it is called infrared. • Wavelength ranges from 10-3 m to 7.8 × 10–7 m. • The frequency ranges from 3 × 1011 Hz to 4 × 1014 Hz. • The infrared wave coming from the sun keeps the earth warm. • In hospitals, they are used in muscular therapy in physiotherapy departments.
  • 36. Visible • Wavelength ranges from 10-3 m to 7.8 × 10–7 m. • The frequency ranges from 3 × 1011 Hz to 4 × 1014 Hz. • Visible light is emitted when electron jump from higher energy level to lower energy level. • Useful in photography, optical microscopy , astronomy etc.
  • 38. Ultraviolet Rays • The wavelength of ultraviolet waves lie nearer to the violet light of visible spectrum. So, it is named ultraviolet. • Wavelength ranges from 4 × 10–7 m down to 6 × 10–10 m. • The frequency ranges from 8 × 1014 Hz to 5 × 1017 Hz. • They are very harmful to the living tissues so can cause skin cancer. • These waves are used to preserve food stuffs as the rays kill germs.
  • 39. X-rays Produced by bombarding target of high atomic number with beam of fast moving electrons. Wavelength ranges from nearly 10–9 m down to 6 × 10–12 m. The frequency ranges from 3 × 1017 Hz to 5 × 1019 Hz. Used in medical diagnosis and therapy.  Are harmful for our body as Biological cells are destroyed, if x-rays are exposed on them.
  • 40. Gamma Rays Produced during radioactive decay of nuclei and nuclear reactions.  Shortest wavelength ranges from nearly 10–10 m below to 10– 14 m.  The frequency ranges from 3 × 1018 Hz to 3 × 1022 Hz. These rays have serious effect on human cells.  Used to kill the cancerous cells in radiotherapy.
  • 41. Sine Wave Sine or sinusoidal wave is the most natural representation of how many things in nature change state. A sine wave shows how the amplitude of a variable changes with time. A sine wave, sinusoidal wave, or just sinusoid is a mathematical curve defined in terms of the sine trigonometric function. It is a type of continuous wave and also a smooth periodic function.
  • 42. The variable could be audible sound.  Example a single pure note is a sine wave, although it would sound a very plain and flat note indeed with none of the harmonics we normally hear in nature.  A straightforward oscillating or alternating current or voltage within a wire can also be represented by a sine wave.
  • 43. The number of times the sine wave goes through a complete cycle in the space of 1 second is called the frequency.  Indeed the unit used to be cycles per second, but now the unit of measurement is hertz (Hz).  A frequency of 1000Hz, or 1 kHz, means that the sine wave goes through 1000 complete cycles in 1 s. If we are considering audible sound waves then the human ear has a frequency range of about 20Hz-20kHz.
  • 44. • The sine of any angle can vary from 1 to +1. − • For example the sine of 0° is 0 and the sine of 90° is 1. • The sine of 270° is 1 and when we get to 360° we are − back to zero again. • A cosine is 90° out of phase with a sine wave
  • 45. COSINE WAVE • The cosine of 0° is 1 and the cosine of 90° is 0. • So we say that a cosine is 90° out of phase with a sine wave. • Any number of sine waves can exist at any one time and have any manner of angular phase differences to each other. • Whenever a phase angle is mentioned it is always relative to something else.
  • 46. • Digital ‘ones’ and ‘zeroes’ can be encoded as two signals of identical amplitude and frequency but with different phases to each other or some other reference marker. • This would be called phase modulation.
  • 47. REFERENCES  PICTURES FROM INTERNET  https://byjus.com/physics/waves/#:~:text=A%20wave%20is%20a %20disturbance,%2C%20electric%20potential%2C%20or%20temperature

Editor's Notes

  • #5: Same amplitude frequency and period Gradual phase difference between successive particles