Background radiation mainly comes from natural sources, which include cosmic rays, soil and rocks and living things, according to the BBC. Artificial radiation originates mainly from types of medical examinations like X-... More » Science Physics Optics & Waves

The spectrum of electromagnetic radiation is comprised of waves or particles that carry different amounts of energy. The visible spectrum is what humans and most animals see. The least energetic range of electromagnetic ... More » Science Physics Magnetism

Cosmic microwave background radiation can be thought of as the echo of the Big Bang. It is the residual energy from the first few hundred-thousand years after the beginning of the universe. According to Universe Today, t... More » Science Physics Particle Physics
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Electromagnetic radiation between 8*10^14 to 3*10^16 Hz (800 THz to 30 PHz) and wavelengths from 10^-8 m to 3.8*10^-7 m (10 nm to 380 nm) are ultraviolet rays. The frequency of waves is inversely proportional to their wa... More » Science Physics Optics & Waves

Ultraviolet radiation, X-rays and gamma rays all have wavelengths that are shorter than visible light. The ultraviolet spectrum ranges from 400 to 10 billionths of a meter, X-rays from about 10 billionths to 10 trilliont... More » Science Physics Optics & Waves

Radio waves are a type of electromagnetic radiation with a very long wavelength that are emitted by sources that include astronomical objects and television and radio transmitters. Radio waves, the longest wavelengths in... More » Science Physics Optics & Waves

Shadows change length due to the constant change in the angle of the sun’s rays. Light falling on an opaque object casts a shadow in the opposite direction to the source of light. More » Science Physics Optics & Waves