Physics Questions Answers

• 64. What is refractive index ?

  1. it is defined as the ratio of speed of light in the medium to the speed of light in vacuum.
  2. it is defined as the ratio of speed of light in vacuum to the speed of light in the medium .
  3. it is defined as the product of speed of light in medium and in vacuum.
  4. None of above

  Answer And Explanation

  Answer: Option B

  Explanation:

  • View Answer
  • Comment on this question

• 65. The angle of reflection is equal to the angle of incidence.

  1. True
  2. False

  Answer And Explanation

  Answer: Option A

  Explanation:

  • View Answer
  • Comment on this question

• 66. The incident ray, reflected ray and normal to the reflecting surface at the incident point all never lie in same plane.

  1. True
  2. False

  Answer And Explanation

  Answer: Option B

  Explanation:

  • View Answer
  • Comment on this question

• 67. Which are the primary Colours ?

  1. Yellow, Green, Blue
  2. Red, Magenta, Blue
  3. Red, Green, White
  4. Red, Green, Blue

  Answer And Explanation

  Answer: Option D

  Explanation:

  Red, Green, Blue are primary colours. All the colours can be produced by them by mixing in different proportions. Interesting :)

  • View Answer
  • Comment on this question

• 68. Device used to measure potential difference between two points in a circuit is ?

  1. Ammeter
  2. Galvanometer
  3. Voltmeter
  4. None of above

  Answer And Explanation

  Answer: Option C

  Explanation:

  • View Answer
  • Comment on this question

• 69. Atom is the smallest part of matter which takes part in chemical reactions.

  1. True
  2. False

  Answer And Explanation

  Answer: Option A

  Explanation:

  • View Answer
  • Comment on this question

• 70. Which of following in not a property of cathode ray.

  1. Cathode rays are invisible and travel in a straight line.
  2. These rays can ionise gases.
  3. These rays can penetrate through thin metal foils.
  4. These rays make materials cool on which they fall.

  Answer And Explanation

  Answer: Option D

  Explanation:

  These rays heat the materials on which they fall.

  • View Answer
  • Comment on this question