Tag: technical terms related to lens

Questions Related to technical terms related to lens

A plane-convex lens has a refractive index of 1.6 and a radius of curvature 60 cm. What is the focal length of the lens? 

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. 50 cm

  2. 100 cm

  3. 200 cm

  4. 150 cm

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Correct Option: B
Explanation:

${R _1} = 60\,cm,\,\,{R _2} = \infty ,\,\,\mu  = 1.6$

$\frac{1}{f} = \left( {\mu  - 1} \right)\left( {\frac{1}{{{R _1}}} - \frac{1}{{{R _2}}}} \right)$
$\frac{1}{f} = \left( {1.6 - 1} \right)\left( {\frac{1}{{60}}} \right)$
$ = f = 100\,cm.$
Hence,
option $(B)$ is correct answer.

Which statement is correct for a zone plate and a lens?

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. Zone plate has multi focii whereas lens has one

  2. Zone plate has one focus whereas lens has multiple focii

  3. Both are correct

  4. Zone plane has one focus whereas a lens has infinite

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Correct Option: A

A small object is placed at a distacne 80 cm to the left of the lens.  The position and nature of image formed due to I lens is 

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. real, 30 cm right of I lens

  2. virual, 80 cm right of I lens

  3. virtual , 30 cm right of II lens

  4. real, 30 cm right of II lens

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Correct Option: C

A point on the principal axis of a lens, to which light rays parallel to the principal axis converge after passing through the lens, is ............

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. Centre of curvature

  2. Origin

  3. Focus

  4. Optical centre

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Correct Option: C
Explanation:

A point on the principal axis of a lens, to which light rays parallel to the principal axis converge after passing through the lens, is  called focus of the lens.


Answer-(C).

For which of the following is $f > 0$:

I. Concave mirror
II. Convex mirror
III. Converging lens
 

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. I only

  2. II only

  3. I and III only

  4. II and III only

  5. I, II, and III

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Correct Option: C
Explanation:

In this style of multiple-choice question, the I, II, and III questions provide you with three possible answers, and the five answer choices list different combinations of those three. Theres an upside and a downside to questions like these. Suppose you know that a concave mirror has f >0 and a convex mirror doesnt, but youre not sure about a converging lens. The downside is that you cant get the right answer for sure. The upside is that you can eliminate B, D, and E, and have a 50% chance of guessing the right answer. As long as youre not afraid to guessand you should never be afraid to guess if youve eliminated an answerthese questions shouldnt be daunting. 
The value of f for a converging lens is positive, so the answer is C . 

Centre point of a lens is called

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. Centre of curvature

  2. Pole

  3. Origin

  4. Optical centre

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Correct Option: D
Explanation:

Centre point of a lens is called the Optical Centre of the lens. Any ray of light passing through it goes un-deviated.


Answer-(D).

A convex and a concave lens separated by distance $d$ are then put in contact. The focal length of the combination

physics lens technical terms related to lens terms related to lenses introduction to lenses and its types

  1. Decreases

  2. Increases

  3. Becomes $0$

  4. Remains the same

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Correct Option: A
Explanation:

$\dfrac{1}{f _r}=\dfrac{1}{f _1}+\dfrac{1}{f _2}-\dfrac{d}{f _1f _2}$

So when are brought in contact $d=0$, hence focal length $f _r$ will decrease .