Light, Reflection and Refraction
The distance between optic centre and principal focus of the lens is known as
  • Twice the focal length
  • Principal axis
  • Focal length
  • Optic centre
Explanation: The distance between the optic center and the principal focus of a lens is known as the focal length. It is a key property of the lens that determines its focusing ability.
The position of the object in a compound microscope is
  • At F
  • At 2F
  • Beyond 2F
  • Between F and 2F
Explanation: In a compound microscope, the object is typically placed between the focal point (F) and twice the focal point (2F) of the objective lens to form an enlarged image.
A convex lens does not produce a
  • Virtual magnified image
  • Virtual diminished image
  • Real diminished image
  • Real magnified image
Explanation: A convex lens can produce virtual, magnified images when the object is placed within the focal length, but it cannot produce a virtual diminished image. Virtual images formed by a convex lens are typically magnified.
The total internal reflection prisms are used in
  • Telescope
  • Camera
  • Simple microscope
  • Periscope
Explanation: Total internal reflection prisms are used in a periscope to redirect light and allow for viewing over obstacles. This principle is also applied in other optical devices, but it's most commonly associated with periscopes.
Which of the following are primary colours?
  • Violet, red and green
  • Blue, cyan and magenta
  • Red, green and blue
  • Red, cyan and blue
Explanation: These are the primary colors of light used in the additive color model, where various combinations of red, green, and blue light create other colors.
When magenta, yellow and cyan are added, the colour obtained is
  • White
  • Blue
  • Green
  • Red
Explanation: Magenta, yellow, and cyan are the primary colors in the subtractive color model. When combined in equal proportions, they absorb all the wavelengths of light, resulting in the color white.
When a ray of light passes from a denser to rarer medium, the reflected ray is
  • Returned
  • Explanation: When a ray of light passes from a denser to a rarer medium (e.g., from water to air), it bends away from the normal due to a decrease in the speed of light. This is a result of refraction.