ELECTROMAGNETIC SPECTRUM DETAILS

GAMMA RAYS
	Wavelength range: 10-14 to 10-10  meter  Frequency range: 3x1018 to 3 x 1022 Hz Production: Nuclear origin. Emitted on disintegration of Nuclei of atoms. Properties: Highly penetrating and uncharged. Exhibits Fluorescence, Phosphorescence, ionization and chemical reaction on photographic plates. Uses: gives information about structure of nuclei.
X-rays
	Wavelength range: 10-10 to 10-8  meter  Frequency range: 3x1016 to 3 x 1018 Hz Production: by striking high speed electrons on heavy target. Properties: All properties of gamma rays but less penetrating. Uses: helpful in medical diagnosis, study of crystal structure.
U V REGION
	Wavelength range: 10-8 to 4x10-7  meter  Frequency range: 8x1014 to 3 x 1016 Hz Production: by sun, arc, spark and ionized gases. Properties: All properties of gamma rays but less penetrating. They can produce photoelectric effect. Uses: used in medical applications. Detection of finger prints, forged documents.
VISIBLE
	Wavelength range: 4x10-7 to 7.8x10-7  meter  Frequency range: 4x1014 to 8 x 1014 Hz Production: radiated from ionized gases and incandescent bodies. Properties: exhibit reflection, refraction, interference, diffraction, polarization, photoelectric effect, sensation of sight. Uses: used in LASER technology.
INFRARED
	Wavelength range: 7.8x10-7 to 10-3  meter  Frequency range: 3x1011 to 4 x 1014 Hz Production: by hot bodies Properties: heating effect on thermo piles and bolometer. Exhibit reflection, refraction, diffraction and photographic action. Uses: used in industry, astronomy & medicine etc.
HERTZIAN WAVES/ MICROWAVES
	Wavelength range: 10-3 to 1 meter.  Frequency range: 109 to 3 x 1011 Hz Production: by spark discharge, by electronic devices such as Klystron & Magnetron. Properties: Reflection, Refraction & Diffraction. Produces spark in gaps and receiving circuits. Uses: used in Radar and MASERs and also to reveal finer details of atomic and molecular structure.
RADIO WAVES
	Wavelength range: 1 TO 104 meter. Frequency range: 10 KHz to 30 GHz Production: oscillating circuits and electronic devices. Properties: exhibits Reflection, Refraction & Diffraction. Uses: used in television and radio broadcast system.

How does mass depend on speed?

In order to answer this question, we have to consider two situations:

a) The object could be at rest in our reference frame.

b) The "object" is never at rest in any (physically realizable) frame of reference.

An electron and a tennis ball belong to situation (a), where as a photon belongs to situation (b)

Let us assume that two masses exist, the mass when object has zero speed 'm0' and mass 'm' when object has speed 'V' as observed in our frame of reference.

When the object has zero speed, it is at rest (as observed by us or by someone accompanying the object), and so 'm0' is called the object's rest mass. It is an intrinsic property of the object.

For instance every electron has rest mass m0=9.11 x 10^-31 Kg.

If we set into motion a tennis ball that is initially at rest, the ball acquires kinetic energy, the energy associated with motion.Its energy increases.

From the equation  E=mC2; it implies that increase in energy will correspond to increase in mass too. We deduce that ball's inertia increases. Thus the mass 'm' of moving ball is greater than the rest mass 'm0'. Hence m>m0 holds for any object with kinetic energy.

In 1905, Einstein summarized his theoretical discovery with sentence,

" The mass (i.e. the inertia) of a body is a measure of its energy content.