Questions
Two similar thin equi-convex lenses, of focal length f each, are kept coaxially in contact with each other such that the focal length of the combination is . When the space between the two lenses is filled with glycerin (which has the same refractive index as that of glass) then the equivalent focal length is . The ratio : will be
detailed solution
Correct option is C
According to lens maker's formula 1f=(μ-1)1R1-1R2 1f=(μ-1)1R-1-R=(1.5-1)2R=1RTwo similar equi-convex lenses of focal length f each are held in contact with each other.The focal length F1 of the combination is given by1F1=1f+1f=2f; F1=f2=R2 .........(i)For glycerin in between lenses, there are three lenses, one concave and two convexFocal length of the curve lens is given 1f'=(1.5-1)-2R=-1RNow, equivalent focal length of the combination is given by1F2=1f+1f'+1f;1F2=1R-1R+1R=1RF2=R ..........(ii) Dividing equation (i) by (ii), we get F1F2=12Similar Questions
Image of the sun is formed by a binconvex lens of focal length f. The image is a circular patch of radius r and is formed on the focal plane of the lens. Choose the correct statement from the following
Want to Improve your productivity
talk to our academic experts now !!
799 666 8865
support@infinitylearn.com
6th Floor, NCC Building, Durgamma Cheruvu Road, Vittal Rao Nagar, HITEC City, Hyderabad, Telangana 500081.
JEE Mock Tests
JEE study guide
JEE Revision Notes
JEE Important Questions
JEE Sample Papers
JEE Previous Year's Papers
NEET previous year’s papers
NEET important questions
NEET sample papers
NEET revision notes
NEET study guide
NEET mock tests