physics test no. 1 | ray optics

Question no. 1

The laws of reflection are valid for :
  only for plane surface
  only for curved surface
  both plane and curved surface
  neither of them

Question no. 2

Consider the two statements :
1) if reflected rays intersect , virtual image is formed .
2) if reflected rays diverge after reflection , real image is formed.
Which of the following statements are correct ?.
  only 1
  only 2
  both
  neither

Question no. 3

Consider the following statements virtual images
1) can be formed on screen .
2) always erected and not always magnified
  only 1
  only 2
  both
  neither

Question no. 4

The working principle of optics fibre is
  Scattering
  Polarization
  Total internal reflection
  Dispersion of light

Question no. 5

When an object is placed under a transparent medium , it appears to be raised. The upward shift is (n is refractive index of medium.)
  Apparant depth × (1/n)
  Real depth×(1/n)
  Apparant depth ×(1-1/n)
  Real depth ×(1-1/n)

Question no. 6

If the focal length of the biconvex lens is 25 m , then the power of lens will be
  + 4.0 D
  + 0.4 D
  +0.04 D
  +0.004

Question no. 7

The refractive index of core and clad of the optics fibre is n₁ and n₂ respectively. Which one is correct for optical fibre ?
  n₁ > n₂
  n₁ < n₂
  n₁ = n₂
  No relation between n₁ and n₂

Question no. 8

An object is placed 10cm in front of concave mirror or radius of curvature 15 cm . The image formation is
  real and inverted , m = 3
  real and inverted , m = -3
  virtual and erect , m = -3
  virtual and erect , m = -3

Question no. 9

A boy 1.5 m tall with his eye level at 1.38 m stands before a mirror fixed on a wall. What should be the minimum length of the mirror so that he can view himself fully ?
  1.5 m
  1.38 m
  0.75 m
  1 m

Question no. 10

Light of wavelength 5000 nm falls o aplane reflecting surface . For what angle of incidence is the reflected ray normal to the incident ray ?
0^o
45^o
  90^o
  180^o

Question no. 11

A concave lens is kept in contact with a convex lens of focal length 20cm . the combination works as a convex lens of focal length 50 cm. What is the power of concave lens ?
  -5 D
  -2 D
  -3 D
  - 4 D

Question no. 12

Which one of the following is not correct ?
  The radius of curvature of a concave mirror is twice its focal length.
  the radius of curvature of a plane mirror is infinity
  Power of convex lens is positive
  Optics fibre is based on refraction

Question no. 13

An optician prescribes a power lens of power -0.5 D , the person is suffering from
  myopia
  hypermetropia
  cataract
  None

Question no. 14

In optical instruments , the lenses are used to form image by the phenomenon of
  Relfection
  Refraction
  Dispersion
  Scattering

Question no. 15

If a speed of light in air is 3 × 10⁸ m/s , then the speed of light in glass (refractive index is 1.5) would be
  3 × 10⁸ m/s
  1.5 × 10⁸ m/s
  2 × 10⁸ m/s
  4.5 × 10⁸ m/s