A Thin Convergent Glass Lens (μg = 1.5) Has A Power Of +5.0 D. When This Lens Is Immersed In A Liquid Of Refractive Index  it Acts As A Divergent Lens Of Focal Length 100 Cm. The Value Of μl must Be:

Why Kaysons ?

Video lectures

Access over 500+ hours of video lectures 24*7, covering complete syllabus for JEE preparation.

Online Support

Practice over 30000+ questions starting from basic level to JEE advance level.

Live Doubt Clearing Session

Ask your doubts live everyday Join our live doubt clearing session conducted by our experts.

National Mock Tests

Give tests to analyze your progress and evaluate where you stand in terms of your JEE preparation.

Organized Learning

Proper planning to complete syllabus is the key to get a decent rank in JEE.

Test Series/Daily assignments

Give tests to analyze your progress and evaluate where you stand in terms of your JEE preparation.



A thin convergent glass lens (μg = 1.5) has a power of +5.0 D. When this lens is immersed in a liquid of refractive index  it acts as a divergent lens of focal length 100 cm. The value of μl must be:


Correct option is






solving, we get 



A perfectly reflecting mirror has an area of 1 cm2. Light energy is allowed to fall on it for one hour at the rate of 10 W/cm2. The force that acts on the mirror is: 


A point source of light is placed 4 m below the surface of water of refractive index 5/3. The minimum diameter of a disc, which should be placed over the source, on the surface of water to cut off all light coming out of water is:


A transparent cube of 15 cm edge contains a small air bubble. Its apparent depth when viewed through one face is 6 cm and when viewed through the opposite face is 4 cm. Then the refractive index of the material of the cube is:   


Time taken by sunlight to pass through a window of thickness 4 mm whose refractive index is 1.5 is: 


A ray of light is incident on the surface of separation of a medium with the velocity of light at an angle 45o and is refracted in the medium at an angle 30o. What will be the velocity of light in the medium


A ray of light falls on a transparent glass slab with refractive index (relative to air) of 1.62. The angle of incidence for which the reflected and refracted rays are mutually perpendicular is: 


A concave mirror of focal length f produces an image n times the size of the object. If the image is real, then the distance of the object from the mirror is:    


A convex mirror of focal length f produces an image (1/n)th of the size of the object. The distance of the object from the mirror is: 


A short linear object of length L lies on the axis of a spherical mirror of focal length f at a distance u from the mirror. Its image has an axial lengthL’ equal to: 


The sun (diameter = D) subtends an angle of θ radians at the pole of a concave mirror of focal length f. The diameter of the image of the sun formed by the mirror is: