Understanding the concept of LIGHT SOUND

SOUND

Anything we hear around us is not is sound but vibration of particles. Vibration is a type of disturbance which propagates by particles of medium.

Sound is not travel but it is a wave that is transferred by particles in the form of vibrations (particles can only transfer the vibrations by one particle to second and 2nd to 3rd and so on by remain their positions).

Without particles, sound has no existence. Sound not travel in space because there are no particles in space. , so we transfer the information in form of signal in space.

Speed of sound in different mediums

Air – 343m/sec

Water – 1437m/sec

Glass – 4540m/sec

Iron – 5120m/sec

According to this, as the medium density increases sound speed also increases.

Effect of temperature- As temperature increases speed of sound increases.

The normal range of sound to hear anything for human is 20hz to 20000hz.

But minimum range of sound which a human can hear is 12hz and maximum is 28000hz.

The sound created by a volcano eruption in 1883 is in range of 180decibel and it can be heard up to 3000 miles (ca. 4,828 km).

the sound created by the explosion of nuclear bomb is in range of 240 to 280+ decibels.

So, we cannot imagine what will be the loudest sound.

LIGHT

Light energy is a traveling Photon which is a form of electromagnetic radiation. Photon is a bundle of energy. 

Speed of light is 3 × 10⁸m/sec. in vacuum. 

As dense as the medium the speed of light will decrease.

Nature of light-

Light has dual nature

1- wave nature- we consider the light have wave nature because light has the property of diffraction, refraction, and interference etc.

2-particle nature- light has particle nature because it emits electrons when it strikes on metal surface called Photoelectric effect.

mass of photon is zero.

Formation of light energy -when we provide heat to an object it is start to emit photons.

The number of emitting photons, depending on temperature of the object. 

Photon having a special property that they can never exist in stable form. They start to travel since their formation.

Intensity of light inversely proportional to square of source distance.

7 properties of light – 

reflection, diffraction ,refraction ,polarization, interference ,dispersion, scattering.

Visible light is made up of seven colors known as VIBGYOR.

V – Violet 

I – Indigo

B – blue

G – green 

Y – yellow 

O – orange 

R – red

Where red light has the longest wavelength while violet light has the shortest wavelength.

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DO THINGS HAVE COLOUR ? How can we see colours

Anything we see around us that have colours are not actually colours but photons travels with different frequencies and our eyes detect that frequencies in form of colours.

How photons travels with different frequencies-

Electrons are revolve around the nucleus in different shells in an atom.

Every particular electron revolve in an particular shell. When photon collide with electrons, the electron absorb the energy of photon.

By absorbing the photon energy, the electron goes to the next energy shell for a short time of period (10^-8 sec)
The electron goes to the next energy shell called excited state.

After 10^-8 sec in excited state, the electron come back to it’s original energy shell called ground state.
When electron come back to ground state, it release the energy of photon which is absorbed by it. It release photon in a particular frequency range. And the whole process is continuous.

The released photon strike on our eyes. The light receptors in eyes can transmit the message to brain and brain can detect the this in form of colour and make an image of that object so that we can see an object which has colour.

There are more than 10 million colour detected.

Black and white are not colour because black is form when all the light Ray’s or all the photons can be absorbed and white is formed when all the light Ray’s are reflected from the surface.

Anything which is transparent can pass all the light Ray’s through it and would be invisible if 100% light rays can pass through it which strike on it.
The range of visible light is 380 – 700nanometer(nm).
And all the colours we can see have in the range of visible light.

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ATOM – smallest unit of life

INDEX

  • 1.INTRODUCTION

  • 2. PARTS OF AN ATOM

  • 2.1 NEUTRON

  • 2.2 PROTON

  • 2.3 ELECTRON

  • 3 NUCLEUS

  • 4. CHARGE OF AN ATOM

  • 5. SHAPE, SIZE AND MASS OF AN ATOM

  • 6. STABILITY

  • 7. FISSION AND FUSION OF AN ATOM

INTRODUCTION

Atom is smallest unit of matter. Every state of matter contain atoms and atom contain electrons, protons and neutrons.

According to some theories the protons, electrons and neutrons are made up by small particles called quarks. And quarks are supposed to be smallest particles

NEUTRON

neutron is a part of nucleus and have no charge so it is neutral.

Only hydrogen atom not have any neutron.

PROTON

proton is a positive charge particle stable in nucleus with neutrons

ELECTRON

electron is a negative charge particle revolve around the nucleus. the electron would not be stable in nucleus because it does not emit enough energy to be a part of nucleus.

NUCLEUS

Protons and neutrons are in stable state in nucleus and the electrons revolve around the nucleus.

Neutrons and protons together called nucleons

The number of proton is called atomic number and the sum of number of proton, neutrons called mass number.

CHARGE OF AN ATOM

Protons have positive charge and electrons have negative charge so electrons attracted toward nucleus by electromagnetic force while neutrons are neutral.so that electrons revolve around the nucleus.

An atom is neutral in charge because the number of protons and electrons in atom are equal.

If the number of electrons are greater then protons, the atom have negative charge or if the electrons are removed from atom, the atom is positively charged. such charged atoms are called ions.

SHAPE, SIZE & MASS OF AN ATOM

The approximate diameter of atom is 1 x 10^-10m to 5 x 10^-10m and aproximate diameter of neucleus of atom is 1 x 10^-15m.

the shape of an atom is not perfectly sphere but is ellipsoid. mostly atom’s shape atom’s shape is prolate or oblate.

Mass of proton = 1.67262 × 10 −27 kg

mass of electron = 9.11 x 10 -28 kg

mass of neutron = 1.674×10−27 kg

About 99.9% mass of an atom contains in nucleus.

STABILITY OF AN ATOM

Mostly stable atoms have equal number of protons and neutrons. The electrons present in outer shell of atom called valence electron.

Inert gases have most stable configuration because the outermost shell of inert gases is completely filled. The valency shell with numbers of electron 2, 8, 18, 32,… are supposed be most stable.

According to another theory, atoms are most stable with number of neucleons 2, 8, 20, 28, 50, 82 and 126. These numbers are also called magic numbers.

FISSION AND FUSION OF AN ATOM

If larger nucleus splits into smaller nuclei, called nuclear fission or if two smaller nuclei combine to make larger nuclei, called nuclear fusion (e.g. in sun, Hydrogen converts into Helium by nuclear fusion).

TO BE CONTINUE…….

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