You are currently viewing LIGHT & OPTICS


Do u know me ?

Yes . U are the form of energy that contains Electromagnetic radition ,that is emitted by hot objects like laser, bulb, sun and by it u make things visible .

The main source of light , the sun emits radiation of different wavelengths .Among these wavelength between 390nm to 600 nm is visible.Smaller than this and bigger than this are invisible.

The more hotter the subject -> the shorter the wavelength.

Do u know my nature –

Yes.U contains both wave nature(sci.Huygens) with transmitting through any medium by energy not matter and Particle nature (sci.Albert Einstein) with emission of particle from metal plate .

Wave nature explains –

Reflection , Refraction,light transmission through vaccum, Interference, Diffraction,Polarization etc.

Particle nature explains –

Photoelectric effect,Comptons scattering of x ray, Ramana effect , absorption of light etc.

What r my properties?

– Indipendence of propagation through medium

– Electric and magnetic field cannot affect u

– Your frequency and colour is always constant but velocity , wavelength and amplitude are variable .

–You always travell in straight line with a speed of 3×10 ^8 m/s

Single wavelength – Monochromatic light

Multiple wavelength – Heterochromatic light / White light –

Your relationship with me –

Wavelength shorter than 295nm is absorbed by my cornea

Wavelength between 350nm to 420 nm can pass cornea but absorbed by Lens . So newly Aphakic patient become sensetive to this wavelength and complains about bluish vision .

Wavelength of 490nm and 580nm is mostly sensetive to my eye .

Can u measure me ?

Yes.Radiometry and Photometry are the two quantitive measurement of U


Optics : Hey u know me ?

Yes .You are the study of sight and behaviour of light ,in other words u are concerned with the genesis and propagation of light .


U contains 2 divisions

Physical optics

This study is concerned with details of the dual nature of light . ( wave nature and Particle/ Quantum nature )

Geometrical optics

This is also known as Ray optics that defines perfectly how light travells through mediums.

The two pillars of u –

Reflection – phenomenon of change in the path of light rays without any change in the medium .

Refraction –Phenomenon of change in the path of light ,when it goes from one medium to another .

N.B – Diffraction and Interference are not accounted in geometrical optics.

Special facts

Gravity can affect the straightness of light rays. When a star dies there occurs a tiny huge mass accumulation with high gravity power , it’s so powerful that even light cannot pass through it . And the whole is known as Blackhole .

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