Q.1
If a wave's speed is 5m/s and it has a wavelength of 2.5m, what is it's frequency?
  • 12.5Hz
  • 2.5Hz
  • 7.5Hz
  • 2Hz
Q.2
Twinkling of stars is due to
  • Scattering of light
  • Reflection of light
  • Refraction of light
  • All of above
Q.3
A real image is formed by a a convex lens, then it is put in contact with a concave lens and again a real image is formed. This image is : ______________
  • shift towards the lens system
  • shift away from the lens system
  • remain in its original position
  • shift to infinity
Q.4
Magnification of lens can be represented as M = .......
  • h'/h
  • -v/u
  • h/h'
  • either (a) or (b)
Q.5
A mirror used as surveillance mirrors in groceries and parking spaces
  • concave
  • convex
Q.6
For total internal reflection to take place ray of light should go from
  • Rarer to denser medium
  • Denser to rarer medium
Q.7
Which colour of light travels fastest in any medium except air ?
  • yellow
  • red
  • violet
  • white
Q.8
A boy uses blue colour of light to find the refractive index of glass. He then repeats the experiment using red colour of light.How will the refractive index of glass be ?
  • the same
  • μ decreases
  • μ increases
  • same as speed of light
Q.9
As the ray of light passes from air to glass, state how the wavelength of light changes.
  • wavelength increases
  • wavelength decreases
  • wavelength remains constant
  • wavelength decreases and then increases
Q.10
A monochromatic beam of light of wavelength λ passes from air into a glass block. choose the correct relation.
  • v = c / λ
  • v = λ / λ'
  • μ = c / v
  • λ / λ' = μ
Q.11
How is scattering of light proportional to wavelength
  • Directly
  • Inversely
  • Does not depend
Q.12
The speed of light in glass is 2 ×km/s. What is the refractive index of glass?
  • 3 / 2
  • 1.5
  • 2 / 3
  • Both A & B
Q.13
Name the factors that affect the lateral displacement of light as it passes through a rectangular glass slab.
  • thickness of block
  • angle of incidence
  • refractive index of glass
  • All of above
Q.14
A plano convex lens (f = 20cm) is silvered at plane surface. Now f will be
  • 20 cm
  • 40 cm
  • 10 cm
  • 30 cm
Q.15
A ray of light is incident on a glass sphere of refractive index 1.5 . What should be the angle of incidence so that the ray which enters the sphere does not come out of the sphere?
  • Tan-1(2/3)
  • sin-1(2/3)
  • 900
  • cos-1(2/3)
Q.16
Focal length of a convex lens will be maximum for
  • Blue light
  • Yellow light
  • Green light
  • Red light
Q.17
A double convex thin lens made of glass (refractive index  = 1.has both radii of curvature of magnitudecm. Incident light rays parallel to the axis of the lens will converge at a distance L such that
  • L = 20 cm
  • L = 10 cm
  • L = 40 cm
  • L = 20 / 3 cm
Q.18
If the distances of an object and its virtual image from the focus of a convex lens of focal length f are 1 cm each, then f is _______________
  • 4 cm
  • (√2 +1) cm
  • 2√2 cm
  • ( 2 + √2 ) cm
Q.19
The angle of incidence for an equilateral prism isWhat should be the refractive index of prism so that the ray is parallel to the base inside the prism?
  • 1.414
  • 1.732
  • 1.33
  • 9/8
Q.20
An object is held 9cm from a convex mirror and produces an image 6cm tall that is 4cm away from the mirror. What is the height of the object?
  • -13.5 cm
  • 13 cm
  • 2.7 cm
  • -2.7 cm
0 h : 0 m : 1 s