Ch 9. Ray Optics And Optical Instruments Flashcards
The radius of curvature of each surface of a biconvex lens is 20cm and the refractive index of the material of the lens is 1.5.
The focal length of the lens is
20 cm
A convex lens of focal length 40 cm and a concave lens of focal length 29 cm are in contact. The power of their combination in diootre is
-2.5
Light year is equal to
9.46 × 10¹⁵
A spherical mirror is immersed in water. It’s focal length will
Remain same
The coefficient of reflection for total internal reflection will be
1
The critical angle for total internal reflection of a ray from any medium to vaccum is 30•Degree. Then velocity of light in the medium will be
μ = 1/sinC, Va/Vm = 1/sinC, Vm = 3× 10⁸ × 1/2 = 1.5 × 10⁸ m/s
V niche a, V niche m, V niche m
In visible spectrum, which colour has larger wavelength
Red
The dispersive power of a prism depends on
Nature of material of prism
The final image formed by a terrestrial telescope is
Virtual and erect compared to the object
The unit of which physical quantity is light year?
Distance
Which of the following is correct for refractive index of mean colour (yellow colour) ?
µ = µr + µv/2
Neeche r and v
Power of parallel sided glass-slab is
Zero
Angular dispersion is equal to
(µv - µr) A
Neeche v and r
Which of the following relations is correct for dispersive power?
ω = µv - µr/µy - 1
Neeche v, r and y
Velocity of light in vacuum is c. its value in glass
(µ = 3/2) will be
2c/3
The power of convex lens of focal length 20 cm in dioptre is
5
The velocity of light is maximum in
Vaccum
The refractive index of diamond is about
2.42
Optical path is equal to
Refractive index × path-length
A convex lens (µ = 1.5) is immersed in water
(µ = 1.33), then it will behave as
Converging lens
Light owes its colour to its
Frequency
The solar spectrum is
Continuous
Which one of the following has maximum refractive index?
Diamond has maximum refractive index
Equivalent focal length of two lenses in contact having power
-15D and +5D will be
-10cm
A convex lens is dipped in a liquid, whose refractive index is equal to refractive index of material of lens. Then it’s focal length will
Become infinite
Critical angle for light moving from medium I to medium II is θ. The speed of light in medium I is v. Then speed in medium II is
V/Sin θ
Magnifying glass is to be used at the fixed object distance of 1 inch. if it is to produce an erect mage 5 times magnified, its focal length should be
1.25”
Which of the following phenomena takes place when monochromatic light is incident on a prism?
Dispersion
The critical angle of light passing from glass to air is minimum for
Violet colour
The angle of minimum deviation for thin prism of refractive index (µ) is
(µ -1) A
The focal length of a lens
µ = 1.5 in air is 20cm. Its focal length in medium of refractive index 1.5 is
♾️
The optical fibre works on the principle of
Total internal reflection