UPSC CSE Prelims 2002 Q69 — Science & Technology PYQ with Answer

Consider the following statements:

1. Light of longer wavelength is scattered much more than light of shorter wavelength.

2. The speed of visible light in water is 0.95 times its speed in vacuum.

3. Radio waves are produced by rapidly oscillating electrical currents.

4. To detect over-speeding vehicles, police use the Doppler effect of reflected short radio waves.

Which of these statements are correct?