Physics Lesson 12.10.1 - Power of Lenses

[ 1 Votes ]

Welcome to our Physics lesson on Power of Lenses, this is the first lesson of our suite of physics lessons covering the topic of Power of Lenses. The Human Eye, you can find links to the other lessons within this tutorial and access additional physics learning resources below this lesson.

Power of Lenses

As we have seen in the previous tutorial, lenses are not all identical even when they belong to the same category. Their radius of curvature determines the point in which parallel rays coming from infinity converge. We called this point as focus, F and numerically, it was equal to half-distance from the lens to the centre of curvature (half of the radius).

There is a new quantity used to determine how able is a lens to collect rays at points near it. This quantity is the reciprocal of focal length and is known as (optical) Power of a lens, P. The only condition is that focal length must be written in metres. Its formula therefore is:

P = 1/F (in metres)

Power of lens is measured in Dioptre [D]. For example, a converging lens of focal length equal to 20 cm (0.2 m) has a power of

P = 1/F
= 1/0.2 m
= 5 dioptres

On the other hand, a diverging lens of focal length equal to 40 cm (0.4 m), has a power of

P = 1/F
= - 1/0.4 m
= - 2.5 dipotres

because the focal length in diverging lenses is taken as negative.

You have reached the end of Physics lesson 12.10.1 Power of Lenses. There are 3 lessons in this physics tutorial covering Power of Lenses. The Human Eye, you can access all the lessons from this tutorial below.

More Power of Lenses. The Human Eye Lessons and Learning Resources

Optics Learning Material
Tutorial IDPhysics Tutorial TitleTutorialVideo
Tutorial
Revision
Notes
Revision
Questions
12.10Power of Lenses. The Human Eye
Lesson IDPhysics Lesson TitleLessonVideo
Lesson
12.10.1Power of Lenses
12.10.2Power of a Combination of Lenses
12.10.3The Human Eye

Whats next?

Enjoy the "Power of Lenses" physics lesson? People who liked the "Power of Lenses. The Human Eye lesson found the following resources useful:

  1. Knowledge Feedback. Helps other - Leave a rating for this knowledge (see below)
  2. Optics Physics tutorial: Power of Lenses. The Human Eye. Read the Power of Lenses. The Human Eye physics tutorial and build your physics knowledge of Optics
  3. Optics Revision Notes: Power of Lenses. The Human Eye. Print the notes so you can revise the key points covered in the physics tutorial for Power of Lenses. The Human Eye
  4. Optics Practice Questions: Power of Lenses. The Human Eye. Test and improve your knowledge of Power of Lenses. The Human Eye with example questins and answers
  5. Check your calculations for Optics questions with our excellent Optics calculators which contain full equations and calculations clearly displayed line by line. See the Optics Calculators by iCalculator™ below.
  6. Continuing learning optics - read our next physics tutorial: Features of Light

Help others Learning Physics just like you

[ 1 Votes ]

We hope you found this Physics lesson "Power of Lenses. The Human Eye" useful. If you did it would be great if you could spare the time to rate this physics lesson (simply click on the number of stars that match your assessment of this physics learning aide) and/or share on social media, this helps us identify popular tutorials and calculators and expand our free learning resources to support our users around the world have free access to expand their knowledge of physics and other disciplines.

Optics Calculators by iCalculator™