Question

Find the focal length of a lens of power -2.0 D. What type of lens is this?

Solution

Given,
Power of the lens, P = -2.0 D

Therefore,
Focal length, $f = \frac{1}{P} = \frac{1}{- 2.0 D} = - 0.5 m .$

Since, focal length is negative, the lens is concave.

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Acids, Bases And Salts

Find the focal length of a lens of power -2.0 D. What type of lens is this?

Some More Questions From Acids, Bases and Salts Chapter

Briefly discuss the various theories about the nature of light.

What is the wavelength range of visible light? What is the importance of this wavelength range?

Define a ray of light and a beam light. What are the different types of beams of light?

What is an optical medium? How can we classify different media on the basis of their behaviour towards light?

What do you mean by reflection, refraction and absorption of light?

Which type of phenomenon (reflection or refraction) occurs when light falls on (i) a highly polished surface like a mirror and (ii) a transparent medium like glass or water?

What is meant by the optical image of an object?

What are real and virtual images? Can these images be obtained on a screen? Give reasons in support of your answer.

Give three points of differences between real and virtual images.

What is a mirror? Mention the different types of mirrors commonly used.

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