Question

what is mean by light​

Answer 1

Explanation:

light is the electromagnetic radiation within the electromagnetic spectrum that can be perceived by the human eye

the wavelength is about 400-700 nanometres between infrared and the uv

Answer 2

Answer:

Although light is bundled as photons, the photons come in the form of waves that move with a group wave velocity c.  And each photon has an energy level defined by E = hf; where h is Planck's constant and f is the frequency of the energy of a photon.  Because light is both photon and wave, we say it has a dual nature.

The group velocity of the waves travels at the speed of light.(c)  Thus, L = ct which is just some distance L a wave travels a the speed c times time t.  But if we designate L to be the length of the group wave, i.e., the wavelength, then t is the period.  And 1/t = f, which is the frequency of the wave.  Therefore, we can write L = ct = c/f; so that Lf = c.  And this remarkable equation says that if the wavelength is shortened, the frequency has to be raised, and vice versa, so that c remains fixed.

Now, returning to the energy equation E = hf.  Another remarkable thing about light is that the group wave frequency and the photonic frequency are the same frequencies.  So all we need to do is add energy E to increase a frequency f of each photon and, concurrently, the group wave.  One way to do that is to add heat energy, say, to a filament in a light bulb.  We add the heat by pushing more electrical current through it, which causes the filament to glow from the heat.

As we add more and more current, we get hotter and hotter temperatures because of the increasing heat energy.  The emitted photon frequencies rise and with faster frequencies,we go from red to green to indigo colors for the light.  And those bluer colors are the result of the higher frequencies and, because Lf = c, shorter wavelengths.

And there you are...pump more current into a lamp bulb filament and the light frequency will go higher and give bluer light.  Reduce the current, and the light will go reder with slower frequencies.  Of course, if you pump in too much current, the filament will burn out and everything will go black.