Question:

Two thin lenses are in contact and the focal length of the combination is $80\, cm$. If the focal length of one lens is $20 \,cm$, then the power of the other lens will be

Updated On: Apr 22, 2024
  • $1.66\, D$
  • $4.00\, D$
  • $-100\, D$
  • $-3.75\, D$
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is D

Solution and Explanation

$P_{2}=P-P_{1}=\frac{100}{80}-\frac{100}{20}=-3.75\quad D$
Was this answer helpful?
0
0

Top Questions on spherical lenses

View More Questions

Questions Asked in VITEEE exam

View More Questions

Concepts Used:

Spherical Lenses

Lenses that are made by combining two spherical transparent surfaces are called spherical lenses.  In general, there are two kinds of spherical lenses. Lenses that are made by joining two spherical surfaces that bulge outward are convex lenses, whereas lenses that are made by joining two spherical surfaces that curve inward are concave lenses.

Properties of Convex lens:

  1. In this, the lenses are thicker in the middle and thinner at the edges.
  2. They have a positive focal length.
  3. It intersects the incident rays towards the principal axis
  4. These lenses are used in the camera, focus sunlight, projector microscope, simple telescope, overhead projector, magnifying glasses, etc.

Properties of Concave lens:

  1. These lenses are thinner in the middle and thicker at the edges.
  2. They have a negative focal length.
  3. It parts the incident rays away from the principal axis.
  4. These are used in the glasses, spy holes, some telescopes in the doors, etc.