Tag: lens

Questions Related to lens

Fill in the blank. 

A _____ is a piece of transparent glass bounded by two spherical surfaces. 

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

  1. lens

  2. mirror

  3. both  

  4. none 

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Correct Option: A
Explanation:

A lens is a piece of transparent glass bounded by two spherical surfaces.


Answer is lens.

The focal length of a lens 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:

focal length is basically length from the optic centre to the focus, so it is expressed in metres

A straight line passing through the two centres of curvature of lens is called

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

  1. Normal

  2. Principal axis

  3. Centre axis

  4. Diameter axis

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Correct Option: B
Explanation:

Principal axis is a straight line passing through the two centres of curvature of lens.

The 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:

The principal axis is also called optical axis of a lens, passing through the optical center of the lens.

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. Efficiency

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Correct Option: D
Explanation:

Aperture of a lens is the length of the surface of lens exposed for incident light.Focal length is the distance between focus of the lens and lens optical center.Principal focus is the focus from which a ray of light traveling parallel to optical axis passes through or appears to pass through after refraction.There is no term like efficiency of a lens.but there is magnification of a lens.

The value of the focal length of the lens is equal to the value of the image distance when the rays are

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

  1. Passing through the optic centre

  2. Parallel to the principal axis

  3. Passing throught he focus

  4. Over the mirror

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Correct Option: B
Explanation:

When the object is placed at infinity, i.e., when the rays are parallel to the principal axis, the value of focal length is equal to the value of the image distance.

i.e., object distance , $u=\infty$
From lens formula,

$\dfrac 1f=\dfrac 1u+\dfrac 1v\\\implies \dfrac 1f=\dfrac 1\infty+\dfrac 1v\\\implies f=v$
i.e., image distance is equal to focal length of the lens.

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

Show answer
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

Show answer
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. $0.8m$

Show answer
Correct Option: B