Question

Given below in the left column are different modes of communication using the kinds of waves given the right column.

A. Optical Fibre Communication	P. Ultrasound
B. Radar	Q. Infrared Light
C. Sonar	R. Microwaves
D. Mobile Phones	S. Radio Waves

Answer 1

Hint: The applications of the optical fiber, radar, sonar and mobile phones helps to remember the light or waves which are used. The frequency range of these will also help to remember their uses. We can just remember them and can easily get the right match.

Complete step-by-step answer:
A. For fiber optics with glass fibers, we use light in the infrared region (IR) which has wavelengths longer than visible light, typically around 850, 1300 and 1550 nm. In fiber optics the scattering of the incident light is caused by light bouncing off atoms or molecules in the glass.
B. The acronym of radar is radio detection and ranging. Radar is a detection system which uses radio waves to determine the range, angle, or velocity of objects or the targets. This system is mostly used in the navy to detect the range or velocity of targets.
C. Acronym of sonar is sound navigation ranging. Sonar, is used in robotics means, it has an ultrasonic emitter and ultrasonic receiver. Also, there are some sonar with a single emitter/receiver. However, they all use ultrasonic sound ways in order to sense the distance to an object.
D.  We all use microwaves as a power transmitter to our mobile phones. For this, we require a sensor, a retina circuit and a filter on our mobile phone. The microwave is sent with the message by the transmitter using an antenna at frequency 2.24 GHz. Microwaves are the short wave ranging between 1GHz to 1000GHz.
Therefore, the correct matching of the right and left column will be A and Q, B and S, C and R and the last one D and P.

Additional Information: The working of Optical fiber is based on total internal reflection or TIR effect. Here, when the critical angle is greater than 90 degree the system observes TIR effect.
Radar is also used on airports and other platforms where detection of range and velocity of the object is being observed.
The term sonar is also used for the equipment used to generate and receive the sound.
Microwaves are also used in ovens as it is a short wave; it makes the food heat faster than the stove.

Note: There are many applications of fiber optics, radar, sonar and microwaves but the basic principle remains the same. The frequency range of infrared light, ultraviolet light, radio waves and microwave are different and they need to be remembered.