# General knowledge:: Physics

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### Exercise

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26

#### Light Emitting Diodes (LED) is used in fancy electronic devices such as toys emit

 A. X-rays B. ultraviolet light C visible light D. radio waves

27

#### Radio telescopes are better than optical telescopes because

 A. they can detect faint galaxies which no optical telescope can B. they can work even in cloudy conditions C they can work during the day and night D. All of the above

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#### Of the four locations mentioned below the highest inside temperature will be attained in the pressure cooker operated with the pressure valve open

 A. at sea level B. at the top of Mt. Everest C at a place in a valley below sea level D. in an aeroplane flying at a height of 10,000 m with inside pressure maintained at the sea level

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#### Intensity of sound at a point is ____ its distance from the source.

 A. directly proportional to B. inversely proportional to C directly proportional to square of D. inversely proportional to square of

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#### Sound produced at a point is heard by a person after 5 second, while the same sound is heard by another person after 6 seconds. If the speed of sound is 300 m/s, what could be the maximum and minimum distances between the two persons?

 A. 1.8 km, 0.15 km B. 2.2 km, 0.20 km C 2.8 km, 0.25 km D. 3.3 km, 0.30 km

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