Class 10 > Unit # 12: Electromagnetic Spectrum > Uses of Electromagnetic Waves

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Electromagnetic Spectrum - Applications and Uses

Q. Explain uses of radio waves.

Uses of Radio Waves

Radio waves have the longest wavelengths in the electromagnetic spectrum.

1. In a radio system, a microphone controls the current to the antenna so that the radio waves pulsate. The incoming pulsations in the radio receiver control a loudspeaker to create a copy of the original sound. Radio waves can diffract around hills, so radio can receive signals even if a hill blocks the direct route from the transmitting antenna. Long waves will also diffract around the curved surface of the Earth.
2. Radio waves are also used in television communication. Radio waves of very high-frequency VHF and ultra high-frequency UHF waves are used to telecast television programs. These waves have shorter wavelengths, and they do not diffract around hills. So, there must be a straight path between the transmitting and receiving antenna for good reception.

Q. Explain uses of microwaves.

Uses of Microwaves

Microwaves have a shorter wavelength in the micrometer range and a higher frequency than all radio waves. These are usually generated inside the specialized oven by an electron tube.

1. Satellite phones use microwaves for communication, and satellite television uses microwaves to receive satellite television programs. Microwaves can penetrate haze, light rain, clouds, and smoke but these waves are highly directional, the satellite dish and related components must be aligned appropriately, without any obstruction between the transmitted satellite signals and receiving satellite dish.

Q. Explain uses of infra red waves.

Uses of Infra Red

Infrared (IR), or infrared light, is electromagnetic radiation (EMR) with wavelengths longer than visible light. Infrared radiation is radiated or absorbed by molecules when they change their rotational-vibrational movements.

1. Infra-red wireless remote controllers control various household electrical appliances that send invisible signals to an infrared receiver on a device such as televisions, video recorders, or hi-fi (High fidelity) systems.
2. The human body also gives out infrared radiations. Intruder alarms use these motion sensors that detect the changing pattern of infrared radiations emitted by a warm body of an approaching person. This characteristic of infrared waves has been used for security purposes particularly in military technology.

Q. Explain use of visible light in endoscope.

Uses of Visible Radiation

The high flexibility of optical fibers makes them also ideal for use in the medical industry.

An endoscope, a medical device, is a long tube consisting of optical fibers that enable doctors to see abnormalities in organs such as the stomach intestines inside a human body.

Q. Explain uses of ultra violet radiation.

Uses of Ultra Violet Radiation

Very hot objects, such as the Sun, emit radiations beyond the violet end of the visible spectrum, known as ultraviolet radiations. The ultraviolet is also produced by passing an electric current through the mercury vapors in the tube. Ultraviolet radiation is further divided into three bands in order of increasing energy UV-A type, UV-B type, and UV-C type.

1. Sunbeds: Ultraviolet lamps that emit UVA and UVB radiation are used in sunbeds for artificial tanning. It is popular in countries with long periods of limited sunlight. Under medically controlled supervision, sunbeds beautify, provide the body with vitamin D, and treat certain skin conditions.
2. Fluorescent Lamps: In fluorescent lamps, the inside of the tube is coated with white powder (fluoresce), which gives off light when it absorbs ultraviolet. They are commonly used in lighting houses, shops, and offices for decorating purposes.
3. Sterilization: As ultraviolet kills harmful bacteria, strong UVB and UVC radiations are used to sterilize food and medical equipment in hospitals.

Q. Explain uses of x rays.

Uses of X-Rays

X-rays are produced when fast-moving electrons lose their energy quickly. For example, in an x-ray tube, the radiation is given off when a beam of fast-moving electrons hits the metal target.

1. The long-wavelength or low-frequency x-rays are highly penetrating that can pass through flesh but not bones. In the medical imaging field, radiologists use low-frequency x-rays to produce the x-ray images to diagnose the fracture in the bones or even tooth decay, tumors, and abnormal masses inside the body.
2. Computed Tomography (CT) scan is a computational diagnostic tool for detecting diseases and injuries. It uses a series of low-frequency X-rays and a computer to produce a 3D image of soft tissues and bones.
3. Radiation Therapy is a cancer treatment that uses controlled doses of high-frequency x-rays to kill cancerous cells and shrink tumors.
4. Industrial radiography is a technique of inspecting materials to detect inside defects by using high-frequency X-rays. In this method, a beam of x-rays points at the tested item. A detector is aligned with the beam on the other side of the item. The detector records x-rays that pass through the Material. The thicker the material, the fewer x-rays can pass through. More rays move through that region because the material is thinner with a crack or flaw.

Q. Explain uses of gamma rays.

Uses of Gamma Rays

Gamma rays come from radioactive materials. They are produced when the nuclei of unstable atoms decay into a stable nucleus or lose energy. They tend to have high energy than x-rays.

1. Gamma rays are used to treat cancer. These high-energy rays are directed at the cancerous tumor to kill cancer cells in oncology.
2. The Gamma Knife Radiosurgery is a medical procedure that uses gamma rays to destroy small tumors in the brain with less damage to surrounding cells.
3. Positron Emission Tomography (PET) is a functional medical imaging method. In a PET scan, a short-lived positron-emitting radioactive sampling taken suitable for a particular function (e.g., brain function) is injected into the body. Radiated positrons quickly fuse with nearby electrons and lead to two gamma rays of 511-keV traveling in opposite directions. After detecting the gamma rays, a computer generates an image that highlights the location of the biological process being examined.
4. Gamma rays are highly penetrating and can pass through metals; because of their extreme power, gamma rays used to radiograph holes and defects in metal castings and other structural parts.

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