Planets do not twinkle because

Q: Planets do not twinkle because

  1. They emit light of a constant intensity
  2. Their distance from the earth does not change with time
  3. They are very far away from the earth resulting in decrease in intensity of light
  4. They are nearer to earth and hence we receive a greater amount of light and, therefore minor variations in the intensity are not noticeable

 

3+

Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to

Q: Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to

  1. the heating effect of current alone
  2. hysteresis loss alone
  3. both the heating effect of current and hysteresis loss
  4. intense sunlight at noon

 

0

Siphon will fail to work if

Q: Siphon will fail to work if

  1. the densities of the liquid in the two vessels are equal
  2. the level of the liquid in the two vessels are at the same height
  3. both its limbs are of unequal length
  4. the temperature of the liquids in the two vessels are the same

 

0