Acids, Bases And Salts

Question

Define linear magnification produced by a lens. Deduce expression for the magnification for (i) convex lens and (ii) concave lens in terms of u and v.

Solution

The linear magnification produced by a lens is defined as the ratio of the size of the image formed by the lens to the size of the object.
It is denoted by m.

Thus,

Magnification,

m = \frac{Size of image}{Size of object} = \frac{h'}{h}

Convex lens:

Here,

∆ AOB ~ ∆ A' OB'

∴

\frac{A' B'}{AB} = \frac{OB'}{OB}

According to new cartesian sign convention,

Size of the image, A' B' = - h' S i z e o f t h e o b j e c t, AB = + h Object distance, OB = - u Image distance, OB' = + v

∴

Magnification =

\frac{- h'}{+ h} = \frac{+ v}{- u}

\frac{h'}{h} = \frac{v}{u}

Thus, Magnification, m = \frac{h'}{h} = \frac{v}{u}

Concave lens:

Here,

∆ AOB ~ ∆ A' OB'

∴

∴

\frac{A' B'}{AB} = \frac{OB'}{OB}

According to new cartesian sign convention,

Image size, A' B' = + h' O b j e c t s i z e, AB = + h Object distance, OB = - u Image distance, OB' = - v

∴

Magnification =

\frac{+ h'}{h} = \frac{- v}{- u}

\Rightarrow

\frac{h'}{h} = \frac{v}{u}

∴ M a g n i f i c a t i o n, m = \frac{h'}{h} = \frac{v}{u}

Some More Questions From Acids, Bases and Salts Chapter

What is light? Mention its two important uses.

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?

For Daily Free Study Material Join wiredfaculty

Acids, Bases And Salts

Define linear magnification produced by a lens. Deduce expression for the magnification for (i) convex lens and (ii) concave lens in terms of u and v.

Some More Questions From Acids, Bases and Salts Chapter

What is light? Mention its two important uses.

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.

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Phone Number

Email Address

Loaction