Question

‼️Please answer with simple explanation‼️
$\huge\underline\red{Question- 1}$
The focal length of a magnifying glass is 25 cm. What is its magnifying power?
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$\huge\underline\red{Question - 2}$
The magnifying power of a simple microscope is 6. What is the focal length of its lens?
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Final results are given, solve the initial part;
1. 4
2. 16.67cm
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Answer 1

Explanation:

ANSWER:-

Here, we need to know that :-

$\boxed{\sf{Power = \dfrac{1}{ Focal \ Length}}}$

On which both the questions depend on.

So, solving further,

The focal length of a magnifying glass is 25 cm.

Centimetre, Remember?

We need to have it as in metre or use:-

$\boxed{\sf{Power = \dfrac{100}{ Focal \ Length}}}$

In order to get the answer in Dioptre.

$\sf{Power = \dfrac{100}{ Focal \ Length}}$

$\sf{Power = \dfrac{100}{ 25}}$

$\sf{Power = 4 \ Dioptre}$

The magnifying power of a simple microscope is 6. What is the focal length of its lens?

6 means, 6 D or Dioptre.

So, using the formula:-

$\boxed{\sf{Power = \dfrac{1}{ Focal \ Length}}}$

$\sf{6 = \dfrac{1}{ Focal \ Length}}$

$\sf{F = \dfrac{1}{ 6} metres }$ is the answer.

And you can convert it into cm by 100/6, hence answer is 16.667 cm.

Answer 2

Answer:1

The near point is taken to be 25 cm, so that a lens of focal length 2.5 cm has an angular magnification of 10. If you bring the object just a little inside the focal plane, the light emerging on the other side will diverge, as it were from a virtual image that is no longer at infinity.

Answer : 2

As we know,

m=1+ fD

⇒6=1+ f25

⇒f=5 cm=0.05 m