# Linear Magnification

## Trending Questions

**Q.**

What is the formula for linear magnification for lens?

v = Image distance

u = Object distance

−vu

vu

uv

−uv

**Q.**

A lens forms the image of an object placed at a distance of 45 cm from it on a screen placed at a distance 90 cm on other side of it. (a) Name the kind of lens. (b) Find : (i) the focal length of lens, and (ii) the magnification of image.

**Q.**

Define the focus (or focal point) and focal length of a convex mirror.

**Q.**Draw a ray diagram for a compound microscope in normal adjustment and least distance of distinct vision

**Q.**The magnification of a convex lens is

- positive
- zero
- infinite
- negative

**Q.**

What do you understand by the term magnification ? Write expression for it for a lens, explaining the meaning of the symbols used.

**Q.**The magnifying power of a simple microscope can be increased, if we use eye-piece of

- higher
- smaller
- infinite

**Q.**

A spherical mirror and a lens are immersed in water. Compare to the way they work in air, Which one do you expect will be more affected by water?

**Q.**

How could you find the focal length of a convex lens rapidly but approximately?

**Q.**

A concave lens forms an erect image of 13rd size of the object which is placed at a distance 30 cm in front of the lens. Find :

(a) the position of image, and

(b) the focal length of the lens.

**Q.**A real image is cast by a lens. What can be said about the magnification produced by the lens?

- Negative
- Zero
- Can’t say
- Positive

**Q.**Convex lens has positive focal length and concave lens has a negative focal length.

- True
- False

**Q.**The near-point of a person suffering from hypermetropia is at 50 cm from his eye. What is the nature and power of the lens needed to correct this defect? (Assume that the near-point of the normal eye is 25 cm).

**Q.**The focal length of a lens is negative.What kind of lens it is?

- Concave
- Cannot be determined
- Convex

**Q.**

Solve these numericals

**c. **If the sum of focal length and radius of curvature is $30cm$, what is the focal length of that spherical mirror?

**Q.**

What happens to the magnifying power of a microscope, when its length increases?

**Q.**A convex lens of focal 20 cm forms an image at a distance of 40 cm on the other side of the lens. Find the distance of the object from the lens. What is the magnification of the object? [4 MARKS]

**Q.**

What is the nature of a mirror having a focal length of $-15cm$?

**Q.**

With the help of a diagram, define the principal focus of

**a.** convex lens

**Q.**At what distance the object should be placed in front of a concave lens of focal length 20 cm so that the image will be formed at distance 10 cm from the lens? What is the magnification of the object?

[4 MARKS]

**Q.**

How does the eye lens change its focal length to see nearby objects?

**Q.**Radius of curvature of a concave lens is 60 cm. What is the focal length?

- -30
- -60
- 60
- 30

**Q.**

If the radius of curvature of a convex mirror is 36 cm, what is its focal length?

**Q.**The object and the image distances are 10 cm & 30 cm respectively for a lens. Image is formed on same side of the object then the focal length is

- 25 cm
- − 10 cm
- + 15 cm
- − 15 cm

**Q.**

A divergence lens of focal length of 30cm forms the image of an object of size 6 cm on the same side as of the object at a distance of 15cm from its optical centre .use lens formula to determine the distance of the object from the lens and the size of image formed ...

Draw a ray daigram to show the formation of image in the above situation .

**Q.**

if a convergent beam of light passes through a diverging lens, the result

may be a converging beam

may be a diverging beam

may be a parallel beam

All of the above

**Q.**

A converging beam of solar rays is incident on a concave spherical mirror whose radius of curvature is $0.8$ m. Determine the position of the point on the principal axis of the mirror, where the reflected rays intersect, if the extensions of the incident rays intersect the principal axis $40$ cm from the mirrors pole?

$10$ cm from the pole

$30$ cm from the pole

$50$ cm from the pole

$20$ cm from the pole

**Q.**Choose the correct ray diagram for a magnifying mirror.

**Q.**

An object is placed at a distance at a distance of 10 cm in front of a concave lens of focal length 10 cm. Find the linear magnification of the lens?

1

13

12

14

**Q.**The maximum magnifying power of a convex lens of focal length 5 cm can be:

- 1
- 25
- 6
- 10