Ray Optics and Optical Instruments-Quiz-2

RAY OPTICS AND OPTICAL INSTRUMENTS - 2

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. A real object is placed in front of a convex mirror (fixed). The object is moving toward the mirror. If v_0 is the speed of object and v_i is the speed of image, then

•  vi less than v0 always
•  vi greater than v0 always
•  vi greater than v0 initially then vi less than v0
•  vi less than v0 initially then vi greater than v0

Solution
As object moves from infinity to the pole of convex mirror, image moves from focus to pole, so, vi is greater than v0, always

Q2.In the above question, if the second car is overtaking at a relative speed of 314 ms^(-1), how fast will the image be moving?

•  -1 ms^(-1)
•  0.5 ms^(-1)
•  0.3 ms^(-1)
•  -0.032 ms^(-1)

Solution

Q3.  The apparent thickness of a thick plano-convex lens is measured once with the plane face upward and then with the convex face upward. The value will be

•   More in the first case
•  Same in the two cases
•  More in the second case
•  Any of the above depending on the value of its actual thickness

Solution

Q4. Two thin lenses are placed 5 cm apart along the same axis and illuminated with a beam of light parallel to that axis. The first lens in the path of the beam is a converging lens of focal length 10 cm whereas the second is a diverging lens of focal length 5 cm. If the second lens is now moved toward the first, the emergent light

•  Remains parallel
•  Remains convergent
•  Remains divergent
•  Changes from parallel to divergent

Solution

Q5. A luminous object and a screen are at a fixed distance D apart. A converging lens of focal length f is placed between the object and screen. A real image of the object in formed on the screen for two lens positions if they are separated by a distance d equal to

•  √(D(D+4f))
•  √(D(D-4f))
•  √(2D(D-4f))
•  √(D^2+4f)

Solution

Q6. For a prism kept in air, it is found that for an angle of incidence 60°, the angle of refraction ‘A’, angle of deviation ‘δ’ and angle of emergence ‘e’ become equal. Then, the refractive index of the prism is

•  1.73
•  1.15
• 1.5
•  1.33

Solution

Q7.A concave mirror is placed on a horizontal table with its axis directed vertically upwards. Let O be the pole of the mirror and C its centre of curvature. A point object is placed at C. It has a real image, also located at C. If the mirror is now filled with water, the image will be

•  Real and will remain at C
•  Real, and located at a point between C and ∞
•   Virtual and located at a point between C and O
•  Real, and located at a point between C and O

Solution

Q8. An isosceles prism of angle 120° has a refractive index of 1.44. Two parallel monochromatic rays enter the prism parallel to each other in air as shown. The rays emerging from the opposite faces

•  Are parallel to each other
•  TAre diverging
•  Make an angle 2 sin^(-1)⁡(0.72) with each other
•  Make an angle 2{sin^(-1)⁡(0.72)-30°} with each other

Solution

Q9.When an object is kept at a distance of 30 cm from a concave mirror, the image is formed at a distance of 10 cm. If the object is moved with a speed of 9 cm s^(-1) the speed with which the image moves is

•  0.1 ms^(-1)
•  1 ms^(-1)
•  3 ms^(-1)
•  9 ms^(-1)

Solution

Q10. A point object ‘O’ is at the centre of curvature of a concave mirror. The mirror starts to move at a speed u, in a direction perpendicular to the principal axis. Then, the initial velocity of the image is

•  2u, in the direction opposite to that of mirror’s velocity
•  2u, in the direction same as that of mirror’s velocity
•  Zero
• u, in the direction same as that of mirror’s velocity

Solution
Image velocity (w.r.t. mirror)=-m× object velocity (w.r.t. mirror) Here m=1