Correct Answer - Option 3 : A-Q, B-S, C-P, D-R
Concept:
1. Optical fibres can be used to transmit light and thus information over long distances. The electromagnetic spectrum is composed of visible and near-infrared light like that transmitted by fibre, and all other wavelengths used to transmit signals such as AM and FM radio and television.
For fibre optics with glass fibres, we use light in the infrared region which has wavelengths longer than visible light, typically around 850, 1300 and 1550 nm.
2. Radar is a detection system that uses radio waves to determine the range, angle, or velocity of objects.
Radio waves (pulsed or continuous) from the transmitter reflect off the object and return to the receiver, giving information about the object's location and speed have frequencies as high as 300 gigahertz (GHz) to as low as 30 hertz (Hz). X-band is a segment of the microwave radio region of the electromagnetic spectrum, within the frequency range 8–12 GHz.
3. Sonar is a system used for the detection of objects under water by emitting sound pulses and detecting or measuring their return after being reflected.
Ultrasonic waves (sounds having frequency greater than 20,000 Hz) are used in sonar because Ultrasonic waves can penetrate water to long distances (because of their high frequency and very short wavelength), but ordinary sound waves or infrasonic waves cannot penetrate water to such long distances.
4. A mobile phone receives microwave signals from a nearby phone (or transmitter) and sends microwave signals back. These short bursts of microwave radiation can transmit a lot of information in a very short time with frequencies between 300 MHz (1 m) and 300 GHz (1 mm).
Therefore, the correct matched pairs are
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Optical Fibre Communication
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Infrared Light
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Radar
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Radio Waves
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Sonar
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Ultrasound
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Mobile Phones
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Microwaves
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Thus, the correct answer is A-Q, B-S, C-P, D-R.
