Flag Engineering Entrance Exams> Two lenses of power 15D and -5D and in co...
question mark

Two lenses of power 15D and -5D and in contact with each other forming a combination lense. What is the focal length of the combination lense? If an object is size 3cm is placed 30cm from this combination lenses. Calculate the position and size the image formed.

Subhalaxmi Rout , 6 Years ago
Grade 10
anser 1 Answers
Eshan

Last Activity: 6 Years ago

Dear student,

The individual powers of a combination of lenses can be added to obtain that of the combination.

HenceP'=P_1+P_2=15D-5D=10D

Hence the focal length of the combinationf'=\dfrac{1}{P'}=10cm

For the object,u=-30cm

Hence\dfrac{1}{v}-\dfrac{1}{u}=\dfrac{1}{f'}
\implies \dfrac{1}{v}=\dfrac{1}{10}-\dfrac{1}{30}=\dfrac{1}{15} \implies v=15cm

Magnification=\dfrac{v}{u}=\dfrac{15}{-30}=-\dfrac{1}{2}

Hence an inverted image of size1.5cmis formed at a distance of15cmfrom the lens.

Provide a better Answer & Earn Cool Goodies

Enter text here...
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free

Enter text here...

question mark
consider the figure of a single riveted lap joint as follows
engineering entrance exams
0 Answer Available

Last Activity: 2 Years ago

question mark
Hello, Can we learn and prepare for MHT-CET online ?
engineering entrance exams
0 Answer Available

Last Activity: 3 Years ago