Ray-Optics-And-Optical-Instruments-Quiz-9

Ray Optics And Optical Instruments Quiz-9

Dear Readers,

As per analysis for previous years, it has been observed that students preparing for NEET find Physics out of all the sections to be complex to handle and the majority of them are not able to comprehend the reason behind it. This problem arises especially because these aspirants appearing for the examination are more inclined to have a keen interest in Biology due to their medical background. 

Furthermore, sections such as Physics are dominantly based on theories, laws, numerical in comparison to a section of Biology which is more of fact-based, life sciences, and includes substantial explanations. By using the table given below, you easily and directly access to the topics and respective links of MCQs. Moreover, to make learning smooth and efficient, all the questions come with their supportive solutions to make utilization of time even more productive. Students will be covered for all their studies as the topics are available from basics to even the most advanced. 

Q81. A spectrum is formed by a prism of dispersive power 'ω'. If the angle of deviation is ‘δ', then the angular dispersion is

•  ω/δ
•  δ/ω
•  1/ωδ
•  ωδ

Solution
                             

Q82.When light travels from one medium to the other of which the refractive index is different, then which of the following will change

•  Frequency, wavelength and velocity
•  Frequency and wavelength
•  Frequency and velocity
•  Wavelength and velocity

Solution
Velocity and wavelength change but frequency remains same

Q83.  The astronomical telescope consists of objective and eye-piece. The focal length of the objective is

•  Equal to that of the eye-piece
•  Greater than that of the eye-piece
•  Shorter than that of the eye-piece
•  Five times shorter than that of the eye-piece

Solution
f_o>f_e for telescope

Q84. If i ̂ denotes a unit vector along incident light ray, r ̂ a unit vector along refracted ray into a medium of refractive index μ and n ̂ unit vector normal to boundary of medium directed towards incident medium, then law of refraction is

•  i ̂.n ̂=μ(r ̂.n ̂)
•   i ̂×n ̂=μ(n ̂×r ̂)
•  i ̂×n ̂=μ(r ̂×n ̂ )
•  μ(i ̂×n ̂ )=r ̂×n ̂

Solution
Snell’s law in vector form is i ̂×n ̂=μ(r ̂×n ̂)

Q85.Combination of two thin lenses of the same material with focal length f₁ and f₂, arranged on a common axis minimizes chromatic aberration. If the distance between them is

•  ((f₁+f₂ ))/4
•  ((f₁+f₂ ))/2
•  (f₁+f₂ )
•  2(f₁+f₂ )

Solution
  ((f₁+f₂ ))/2

86 For a convex lens, if real image is formed the graph between (u+v) and u or v is as follows

•  -3.75 D
•  1.66 D
•  4.00 D
•  -1.00 D

Solution
For convex lens (for real image) u+v≥4f For u=2f,v is also equal to 2f Hence u+v=4f

Q87.At what distance from a convex lens of focal length 30 cm, an object should be placed, so that the size of the image be 1/2th of the object?

•  30 cm
•  60 cm
•  15 cm
•  90 cm

Solution
                             

Q88.A beaker containing liquid is placed on a table, underneath a microscope which can be moved along a vertical scale. The microscope is focussed, through the liquid onto a mark on the table when the reading on the scale is a. It is next focused on the upper surface of the liquid and the reading is b. More liquid is added and the observations are repeated, the corresponding readings are c and d. The refractive index of the liquid is

•  (d-b)/(d-c-b+a)
•  (b-d)/(d-c-b+a)
•  (d-c-b+a)/(d-b)
•  (d-b)/(a+b-c-d)

Solution
                                    

Q89.Which one of the following statements is true

•  An object situated at the principle focus of a concave lens will have its image formed at infinity
•  Concave mirror can give diminished virtual image
•  Given a point source of light, a convex mirror can produce a parallel beam of light
•   The virtual image formed in a plane mirror can be photographed

Solution
Virtual image is seen on the photograph

Q90. An object 2.5 cm high is placed at a distance of 10 cm from a concave mirror of radius of curvature 30 cm. The size of the image is

•  9.2 cm
•  10.5 cm
•  5.6 cm
•  7.5 cm

Solution