Consider the following statements: 1. Light of longer wavelength is scattered much more than the light of shorter wavelength. 2. The speed of visible light in water is 0.95 times and speed in vacuum. 3. Radio waves are produced by rapidly oscillating elec

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Q: 69 (IAS/2002)
Consider the following statements:
1. Light of longer wavelength is scattered much more than the light of shorter wavelength.
2. The speed of visible light in water is 0.95 times and speed in vacuum.
3. Radio waves are produced by rapidly oscillating electrical currents.
4. To detect the over speeding vehicles, police use the Doppler effect of reflected short radio waves
Which of these statements are correct ?

question_subject: 

Science

question_exam: 

IAS

stats: 

0,50,81,21,27,33,50

keywords: 

{'doppler effect': [0, 0, 1, 0], 'radio waves': [1, 2, 3, 2], 'short radio waves': [0, 0, 1, 0], 'longer wavelength': [0, 0, 1, 2], 'shorter wavelength': [0, 0, 1, 1], 'visible light': [0, 0, 6, 6], 'speed': [0, 1, 2, 0], 'light': [16, 4, 34, 62], 'vehicles': [0, 0, 1, 8], 'police': [2, 0, 4, 4]}

The correct statements are:

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

This statement is incorrect. In reality, light of shorter wavelength (such as blue or violet light) is scattered more than light of longer wavelength (such as red or orange light). This phenomenon is known as Rayleigh scattering.

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

This statement is correct. The speed of light in a medium, such as water, is generally less than its speed in a vacuum. The refractive index of water is approximately 1.33, indicating that light travels at approximately 0.75 times the speed of light in a vacuum.

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

This statement is correct. Radio waves are a form of electromagnetic radiation that is generated by rapidly oscillating or alternating electrical currents. These waves have longer wavelengths and lower frequencies compared to visible light.

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

This statement is correct. The Doppler effect can be used to measure the change in frequency of waves caused by the relative motion between the source of the waves and the observer. Police can use this effect by emitting short radio waves and detecting the reflected waves from moving vehicles. By analyzing the frequency shift of the reflected waves, they can determine the speed of the vehicles.

Therefore, the correct answer is 3 and 4.

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