Ray Optics and Optical Instruments-Quiz-11

RAY OPTICS AND OPTICAL INSTRUMENTS-11 Quiz

Dear Readers,

JEE Advanced Physics Syllabus can be referred by the IIT aspirants to get a detailed list of all topics that are important in cracking the entrance examination. JEE Advanced syllabus for Physics has been designed in such a way that it offers very practical and application-based learning to further make it easier for students to understand every concept or topic by correlating it with day-to-day experiences. In comparison to the other two subjects, the syllabus of JEE Advanced for physics is developed in such a way so as to test the deep understanding and application of concepts..

Q1. An object is kept at a distance of 16 cm from a thin lens and the image formed is real. If the object is kept at a distance of 6 cm from the same lens, the image formed is virtual. If the sizes, of the images formed are equal, the focal length of the lens will be

•  15 cm
•  17 cm
•  21 cm
•  11 cm

Solution

Q2.A ray of light falls on a transparent sphere with centre at C as shown in figure, The ray emerges from the sphere parallel to line AB. The refractive index of the sphere is

•  0
•  π/6
•  π/4
•  π/3

Solution

Q3.  A point source S is placed at the bottom of different layers as shown in figure. The refractive index of the bottom most layer is μ_0. The refractive index of any other upper layer is, A ray of light starts from the source S as shown. Total internal reflection takes place at the upper surface of a layer having n equal to

•   3
•  5
•  4
•  6

Solution

Q4. A ray of light from a denser medium strikes a rarer medium at an angle of incidence i. The reflected and refracted rays make an angle of π/2 with each other. If the angles of reflection and refraction are r and r^', then the critical angle will be

•  tan^(-1)⁡(sin⁡i)
•  sin^(-1)⁡(sin⁡r)
•  sin^(-1)⁡(tan⁡i)
•  sin^(-1)⁡(tan⁡r)

Solution

Q5.A cubical room is formed with six plane mirrors. An insect moves along the diagonal of the floor with uniform speed. The velocities of its image in two adjacent walls are 20√2 cm s^(-1). Then, the velocity of the image formed by the roof is

•  20 cm s^(-1)
•  20 √2 cm s^(-1)
•  40 cm s^(-1)
•  10√2 cm s^(-1)

Solution

v cos⁡45°=20√2 Or v/√2=20√2 or v=40 cm s^(-1) The velocity of the image formed by the roof is the same as the velocity of insect So, (c) is the correct choice

Q6. A liquid of refractive index 1.6 is contained in the cavity of a glass specimen of refractive index 1.5 as shown in figure. If each of the curved surfaces has a radius of curvature of 0.20 m, the arrangement behaves as a

•  Converging lens of focal length 0.25 m
•  Diverging lens of focal length 0.25 m
•  Diverting lens of focal length 0.17 m
•  Converging lens of focal length 0.72 m

Solution


Power of liquid lens =(1.6-1)(2/0.20)=6/10×10=6 D Power of concave lens =-(1.5-1)=-0.5×10 D Total power of two concave lenses =-10 D Power of system =-10 D+6 D=-4 D Focal length =1/(-4)=-0.25 m

Q7. A concave spherical refractive surface with radius R separates a medium of refractive index 5/2 from air. As an object is approaching the surface from far away from the surface along the central axis, its image

•  Always remains real
•  Always remains virtual
•  Changes from real to virtual at a distance 2R/3 from the surface
•  Changes from virtual to real at a distance 2R/3 from the surface

Solution

Q8. A man is walking under an inclined mirror at a constant velocity V ms^(-1) along the X-axis. If the mirror is inclined at an angle θ with the horizontal, then what is the velocity of the image?

•  Positive x-axis
•  TNegative x-axis
•  Positive y-axis
•  Negative y-axis

Solution

Q9.A spherical mirror forms an image of magnification 3. The object distance, if local length of mirror is 24

•  32 cm, 24 cm
•  32 cm, 16 cm
•  32 cm only
•  16 cm only

Solution

m=f/(f-u) 3=(-24)/(-24-u) Or -24-u=-8 or u+24=8 Or u=(8-24)cm=-16 cm If m=-3, then -3=(-24)/(-24-u) u+24=-8 Or u=-32 cm Note that the magnification is greater than 1, so mirror cannot be convex

Q10. A concave refractive surface of a medium having refractive index μ produces a real image of an object (located outside the medium) irrespective of its location. Choose the correct option from the following

•  Always
•  May be if refractive index of surrounding medium is greater than μ
•  May be if refractive index of surrounding medium less than μ
• None of the above

Solution