Ray Optics and Optical Instruments-Quiz-3

RAY OPTICS AND OPTICAL INSTRUMENTS - 3

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. Let r and r^' denote the angles inside an equilateral prism, as usual, in degrees. Consider that during some time interval from t=0 to t=t,r^' varies with time as r^'=10+t^2. During this time, r will vary as (assume that r and r^' are in degree)

•  50-t^2
•  50+t^2
•  60-t^2
•  v60+t^2

Solution
In a prism :r+r^'=A ⇒ r=A-r^' ∴r=60°-(10+t^2 )=50-t^2

Q2.In the arrangement shown below, the image of the extended object as seen by the observer is

•  Real and inverted
•  Real and erect
•  Virtual and inverted
•  Virtual and erect

Solution

Q3.  An object is placed 1 m in front of the curves surface of a plano-convex lens whose plane surface is silvered. A real image is formed in front of the lens at a distance of 120 cm. Then, the focal length of the lens is

•   100 cm
•  120 cm
•  109.1 cm
•  110.0 cm

Solution

Q4. A ray of light is incident on a glass sphere of refractive index 3/2. What should be the angle of incidence so that the ray which enters the sphere does not come out of the sphere?

•  tan^(-1)⁡(2/3)
•  60°
•  90°
•  30°

Solution

Q5. A mango tree is at the bank of a river and one of the branch of tree extends over the river. A tortoise lives in the river. A mango falls just above the tortoise. The acceleration of the mango falling from tree as it appears to the tortoise is (refractive index of water is 4/3 and the tortoise is stationary)

•  g
•  3g/4
•  4g/3
•  None of these

Solution

Q6. For the same statement as above, the ratio of the two image sizes for these two positions of the lens is

•  [(D-d)/(D+d)]^2
•  [(D+d)/(D-d)]^2
• [(D-2d)/(D+2d)]^2
•  [(D+2d)/(D-2d)]^2

Solution

Q7.Consider the situation shown in figure. Water (μ=4/3) is filled in a breaker upto a height of 10 cm. A plane mirror is fixed at a height of 5 cm from the surface of water. Distance of image from the mirror after reflection from it of an object O at the botton of the breaker is

•  15 cm
•  12.5 cm
•   7.5 cm
•  10 cm

Solution

Distance of first image (I_1) formed after refraction from the plane surface of water is 10/(4/3)=7.5 cm From water surface (d_app=d_actual/μ) Now, distance of this image is 5+7.5=12.5 cm from the plane mirror. Therefore, distance of second image (I_2) will also be equal to 12.5 cm from the mirror

Q8.The diagram shows a concavo-convex lens μ_2. What is the condition on the refractive indices so that the lens is diverging?

•  2μ_3 less than μ_1+μ_2
•  T2μ_3 > μ_1+μ_2
•  μ_3>2(μ_1-μ_2)
•  None of these

Solution

Q9.A cubical block of glass, refractive index 1.5, has a spherical cavity of radius r=9 cm inside it as shown in figure. A luminous point object O is at a distance of 18 cm from the cube (see figure). What is the apparent position of O as seen from A?

•  17 cm, left of S_4
•  25 cm, right of S_4
•  13 cm, left of S_4
•  10 cm, right of S_4

Solution

Q10. The given lens is broken into four parts rearranged as shown. If the initial focal length is f, then after rearrangement the equivalent focal length is

•  f
•  f/2
•  f/4
• 4f

Solution