Physics
Rainbows are produced when sunlight :

None of the given statements is correct.
Incident on rain drops hanging in the atmosphere is dispersed after suffering refraction and internal reflection.
Incident on raindrops hanging in the atmosphere is dispresed after suffering reflection.
Incident on rain drops hanging in the atmosphere is dispersed after suffering refraction

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Physics
Railway tracks are banked on curves so that

No frictional force may be produced between the tracks and the wheels of the train
Necessary centripetal force may be obtained from the horizontal component of the weight of the train
The train may not fall down inwards
Necessary centrifugal force may be obtained from the horizontal component of the weight of the train

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