1. Put the words in the right order to make a sentence:

1. Or, of, in, off, the, any, dish, microwaves, their, radar, pulses, radio, antenna, waves, object, or, which, path, transmits, bounce. 2. Fog, sleet, are, to, such, clouds, and, visible, transparent, waves, as, rain, snow, that, such, falling, block, things, light, usually, radio. 3. In, are, not, the, as, the, receivers, always, same, radar, usually, location, but, transmitter. 4. Has, directions, signals, a, called, radar, in, radio, that, system, emits, transmitter, waves, radar, predetermined. 5. Radar, Britain, in, during, and, practical, II, nations, was, World, other, War, developed, secrecy, by. 6. Has, English, radar, noun, all, the, since, languages, losing, term, entered, and, the, capitalization, common, other, as, radar. 7. Reflected, desirable, are, make, the, towards, radar, as, radar, back, transmitter, that, work, signals, the, ones, make. 8. With, into, they, are, or, in, when, contact, usually, scattered, directions, these, an, reflected, many, come, object, and.

2. Fill in the blanks with the following words:

Common, Doppler, acronym, reflected, range, secrecy, signals, regardless, weak, conductivity

1. Radar is an object-detection system which uses electromagnetic waves to determine the … , altitude, direction, or speed of both moving and fixed objects. 2. The … absorption of radio waves by the medium through which it passes is what enables radar sets to detect objects at relatively-long ranges. 3. The radar … that are reflected back towards the transmitter are the desirable ones that make radar work. 4. The term radar has since entered the English and other languages as the … noun radar, losing all capitalization. 5. In particular, there are weather conditions under which radar works well … of the weather. 6. Although the … radar signals captured by the receiving antenna are usually very weak, these signals can be strengthened by the electronic amplifiers that all radar sets contain. 7. Radar signals are reflected especially well by materials of considerable electrical … . 8. If the object is moving either closer or farther away, there is a slight change in the frequency of the radio waves, due to the … effect. 9. Practical radar was developed in … during World War II by Britain and other nations. 10. The term RADAR was coined in 1940 by the U.S. Navy as an … for radio detection and ranging.

3. Complete the following sentences using active vocabulary:

1. … transmits pulses of radio waves or microwaves which bounce off any object in their path. 2. … are avoided in designing radars except when detection of these is intended. 3. The radar signals that are reflected back towards the transmitter are … . 4. Radar receivers are usually, but not always, in … . 5. … , or speed of both moving and fixed objects such as aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. 6. The object returns a tiny part of the wave's energy to a dish or antenna which … . 7. The weak absorption of radio waves by the medium through which it passes is … . 8. There are weather conditions under which … . 9. Some of these make the use … . 10. … in secrecy during World War II by Britain and other nations.