A student used a device (X) to obtain/focus the image of a well illuminated distant building on a screen (S) as shown alongside in the diagram. Select the correct statement about the device (X).
  • This device is a concave lens of focal length 8 cm.
  • This device is a convex mirror of focal length 8 cm.
  • This device is a convex lens of focal length 4 cm.
  • This device is a convex lens of focal length 8 cm.
A student obtains a sharp image of the distant window (W) of the school laboratory on the screen (S) using the given concave mirror (M) to determine its focal length. Which of the following distances should he measure to get the focal length of the mirror?
  • MW
  • MS
  • SW
  • MW- WS
The mirror having reflection surface curved outward
  • plane mirror
  • concave mirror
  • convex mirror
  • cylindrical mirror
The mirror having reflecting surface curved inwards
  • plane mirror
  • convex mirror
  • cylindrical mirror
  • concave mirror
The mirror used as rear-view mirror in vehicles
  • convex mirror
  • plane mirror
  • cylindrical mirror
  • concave mirror
The deviation of light ray from its path when it travels from one transparent medium to another transparent medium is called
  • reflection
  • refraction
  • dispersion
  • scattering
Convex lens is also known as
  • converging lens
  • diverging lens
  • radial lens
  • axial lens
The image which is formed behind the mirror
  • real image
  • virtual image
  • blue image
  • partial image
Which of these is false for refractive index?
  • a. It depends on the angle of the incidence
  • b. None of these
  • c. It has no units
  • d. it depends on the nature of the medium
  • e. The lights rays bends more in glass then in water
Two medium X and Y with refractive index 1.31 and 1.50 are given.?Which of the following is false
  • a. Y will bend the light more
  • b. None of these
  • c. The speed of the light will be more in X
Concave lens always provide?
  • a. Erect and diminished image
  • b. erect and magnified images
  • c. None of these
  • d. Inverted and diminished image
Where should an object be placed, so that a real and inverted image of the same size is obtained by a Convex lens?
  • a. at infinity
  • b. between the optical center of the lens and its focus
  • c. at the focus of the lens
  • d. at twice the focal length
The focal length and power of the combination of the convex and concave lens of same focal length placed in contact with each other?
  • a. twice the focal the of the single lens and half the power of the single lens
  • b. zero, infinite
  • c. infinite, zero
  • d. half the focal length, twice the power of the single lens
A convex lens X and A convex lens Y of focal length 10 cm and 25 cm are placed in close contact with one other.
  • a. Dioptres
  • b. No units
  • c. None of these
What is power of the this combination
  • a. 6
  • b. 14
  • c. 1
  • d. None of these
What is the focal length of this combination?
  • a. 35cm
  • b. 7.1cm
  • c. 5 cm
  • d. None of these
The refractive index of glass with respect to water is 1.The refractive index of glass with respect to air is 1.5 What will be the refractive index of water with respect to air?
  • a. 1.6
  • b. None of these
  • c. 1.33
  • d. 1.9
  • e. 1.2
A convex lens has a focal length of 30 cm. Calculate at what distance should the object be placed from the lens so that it forms an image at 60 cm on the other side of the lens?
  • a. None of these
  • b. 30 cm
  • c. 25 cm
  • d. 60 cm
The power of the lens is +2.5D. What is the nature and focal length of the lens?
  • a. Convex,20 cm
  • b. Convex,40 cm
  • c. Concave,20 cm
  • d. Concave,40 cm
An object of length 4cm is placed at a distance 20cm from a convex lens of focal length 10 cm. What is the length and nature of the image?
  • a. 2cm, inverted virtual
  • b. 4cm, inverted real
  • c. 2cm, inverted real
  • d. 4cm, inverted virtual
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