Refractive Index
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Q. Two identical thin plano-convex glass lenses (refractive index 1.5) each having radius of curvature of 20 cm are placed with their convex surfaces in contact at the centre. The intervening space is filled with oil of refractive index 1.7. The focal length of the combination is
- −20 cm
- −50 cm
- −25 cm
- 50 cm
Q. The value of absolute refractive index is always greater than 1.
- False
- True
Q. Velocity of light in glass whose refractive index with respect to air is 1.5 is 2×108m s−1 and in certain liquid the velocity of light found to be 2.50×108m s−1.The refractive index of the liquid
with respect to air is
with respect to air is
- 0.64
- 0.8
- 1.2
- 1.44
Q. What is the relation between refractive indices μ, μ1 and μ2 if the behaviour of light rays is as shown in figure.
- μ>μ2>μ1
- μ<μ2<μ1
- μ<μ2;μ=μ1
- μ2<μ1;μ=μ2
Q. What is the relation between refractive indices μ, μ1 and μ2 if the behaviour of light rays is as shown in figure.
- μ>μ2>μ1
- μ<μ2<μ1
- μ<μ2;μ=μ1
- μ2<μ1;μ=μ2
Q.
Refractive index for a material for infrared light is
[CPMT 1984]
Equal to that of ultraviolet light
Less than for ultraviolet light
Equal to that for red colour of light
Greater than that for ultraviolet light
Q. In the adjoining diagram, a wavefront AB, moving in air is incident on a plane glass surface XY. Its position CD after refraction through a glass slab is shown also along with the normals drawn at A and D. The refractive index of glass with respect to air (μ=1 ) will be equal to
- sin θsin θ′
- sin θsin ϕ′
- sin ϕ′sin θ
- ABCD
Q.
The refractive index of a piece of transparent quartz is the greatest for
[MP PET 1985, 94]
Red light
Violet light
Green light
Yellow light
Q. A thin biconvex lens is made with a material having refractive index μ=1.5. It is dipped in water (μ=1.33). It will behave like
- A converging lens
- A diverging lens
- A rectangular slab
- A prism
Q.
A monochromatic beam of light passes from a denser medium into a rarer medium. As a result [CPMT 1972]
Its velocity increases
Its velocity decreases
Its frequency decreases
Its wavelength decreases
Q. A ray incident at an angle of incidence 60∘ enters a glass sphere of refractive index μ=√3. This ray is reflected and refracted at the farther surface of the sphere. The angle between reflected and refracted rays at this surface is
- 90∘
- 60∘
- 70∘
- 40∘