Tag: physics

Questions Related to physics

Fill in the blanks:

Principal axis is also called ________ of the lens.

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

  1. Optical axis

  2. x-axis

  3. y-axis

  4. axis

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Correct Option: A
Explanation:

Principal axis is also called optical axis of the mirror or lens .

The focal length can be expressed in:

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

  1. metre

  2. Dioptre

  3. Watt

  4. Horse power

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Correct Option: A
Explanation:

The focal length is associated with distance. So, it can be expressed in metre.

Which of the following term is not associated with a lens?

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

  1. Aperture

  2. Focal length

  3. Principal focus

  4. Momentum

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Correct Option: D
Explanation:

The term momentum is not associated with a lens. It is the product of mass and velocity of a body.

A thin plano-convex lens acts like concave mirror of focal length $0.2m$ when silvered at its plane surface. Refractive index of the material of lens is $1.5$. Radius of curvature of convex surface of the lens is

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

  1. $0.1m$

  2. $0.2m$

  3. $0.4m$

  4. $0.8m$

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Correct Option: B

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

Show answer
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).