Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Geometrical Optics question

2013 · Q132
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /NEET
  3. /Physics
  4. /Geometrical Optics
  5. /2013 · Q132

Geometrical Optics question

2013 · Q132

NEETPhysicsGeometrical OpticsMCQ+4 / −1
A plano convex lens fits exactly into a plano concave lens. Their plane surfaces are parallel to each other. If lenses are made of different materials of refractive indices μ\muμ1 and μ\muμ2 and R is the radius of curvature of the curved surface of the lenses, then the focal length of the combination is
  1. A
    R(μ1−μ2){R \over {\left( {{\mu _1} - {\mu _2}} \right)}}(μ1​−μ2​)R​
  2. B
    2R(μ2−μ1){{2R} \over {\left( {{\mu _2} - {\mu _1}} \right)}}(μ2​−μ1​)2R​
  3. C
    R2(μ1+μ2){R \over {2\left( {{\mu _1} + {\mu _2}} \right)}}2(μ1​+μ2​)R​
  4. D
    R2(μ1−μ2){R \over {2\left( {{\mu _1} - {\mu _2}} \right)}}2(μ1​−μ2​)R​
View written solutionFree

Correct answer: A

NEET 2013 Physics - Geometrical Optics Question 64 English Explanation


Equivalent focal length is $${1 \over {{f_{eq}}}} = {1 \over {{f_1}}} + {1 \over {{f_2}}}$$

$ \Rightarrow $ ${1 \over {{f_{eq}}}}$ = $$\left( {{\mu _1} - 1} \right)\left( {{1 \over \infty } - {1 \over { - R}}} \right)$$ + $$\left( {{\mu _2} - 1} \right)\left( {{1 \over { - R}} - {1 \over \infty }} \right)$$

$ \Rightarrow $ feq = $${R \over {\left( {{\mu _1} - {\mu _2}} \right)}}$$
PreviousNext

More from Geometrical Optics

  • A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 cm in such a way that its enf closer to the pole is 20 cm away from the mirror. The length of the image is2012 · MCQ
  • For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index.2012 · MCQ
  • A ray of light is incident at an angle of incidence i, on one face of a prism of angle A (assumed to be small ) and emerges normally from the opposite face. If the refractive index of the prism is μ. the angle of incidence i, is…2012 · MCQ
  • When a biconvex lens of glass having refractive index 1.47 is dipped in a liquid, it acts as a plane sheet of glass. This implies that the liquid must have refractive index2012 · MCQ
  • A concave mirror of focal length f1 is placed at a distance of d from a convex lens of focal length f2. A beam of light coming from infinity and falling on this convex lens − concave mirror combination returns to infinity. The…2012 · MCQ
  • The magnifying power of a telescope is 9. When it is adjusted for parallel rays the distance between the objective and eyepiece is 20 cm. The focal length of lenses are2012 · MCQ
  • A thin prism of angle 15o made of glass of refractive index μ1 = 1.5 is combined with another prism of glass of refractive index μ2 = 1.75. The combination of the prisms produces dispersion without deviation. The angle of the…2011 · MCQ
  • A converging beam of rays is incident on a diverging lens. Having passed through the lens the rays intersect at a point 15 cm from the lens on the opposite side. If the lens is removed the point where the rays meet will move 5 cm closer to…2011 · MCQ